It's unclear, but you likely come to life with restored spell slots
For the sake of context, let's imagine that a 17th level Wizard casts the Clone spell, targeting themselves. Then years later (say they are now level 20), they enter into an epic battle as part of a war. They fight valiently, but run completely out of spell slots on the field. They fight with cantrips for a time, but eventually the swords and axes of their enemies are too much, and they drop. They are attacked while dying several times, forcing failed death saving throws, and they die.
What happens next? Will the clone that awakens have its spell slots restored, or not?
Well, before we go any further, let's establish one important detail:
Does the Clone spell copy a creature's qualities when the spell is cast, or when the creature dies?
In the above example, we have a 17th level wizard who clones himself, but then is 20th level when he dies. So which version is the clone spell meant to emulate? The 17th level one, or the 20th level one?
Here, the text of the spell (bold added) can give us some guidance:
if the original creature dies, its soul transfers to the clone, provided that the soul is free and willing to return. The clone is physically identical to the original... The original creature's physical remains, if they still exist, become inert and can't thereafter be restored to life...
In this text, we see that "the original" refers to the creature that dies, and left behind remains. And that the clone is identical to "the original." No 17th level wizard died and left behind remains: a 20th level wizard did. What the wizard used to be (e.g. 17th level, 18th level, a toddler) is not what the spell is reproducing, but rather the creature that just died. So we can safely say that the creature created by the clone spell is to be compared to the original creature at the time of death.
(I know that was a weird segue: trust me, it will be useful later).
Ok, fine. It is copying the 20th level wizard. Now does the copy have the spell slots restored or not?
As always, it's worth looking to the text of the Clone spell first, the most relevant section of which is probably this one:
The clone is physically identical to the original and has the same personality, memories, and abilities, but none of the original's equipment.
This statement gives us some guidance, but it's open-to-interpretation at best. Does a spell slot count as an ability? Memories? Personality? Equipment? Some of these categories are more viable than others (i.e. existing answers have tried to categorize a spell slot, or a lack of a spell slot, as an Ability), but none are ideal.
One thing we can say with certainty is that spell slots are a resource: one that recharges under certain circumstances, like a long rest, and allows a creature to do certain things while they have them. So...
So what happens to the original creature's "resources"?
Again, the rules here are unclear.
You could make an argument saying that a target's spell slots being considered as a resource means the Wizard loses the spell slots: perhaps pointing out that equipment is also a resource of a kind, and that the clone has "none of the original's equipment." But I put it to you that such an argument is doomed to failure for one simple reason:
Hit points are also a resource in this game. Like spell slots, they determine which of your abilities you can use, and which you cannot (for example, a high level Monk could still use their Diamond Soul ability at 0 hp). Like spell slots, they recharge on a long rest. And like spell slots, the wizard in our hypothetical example was entirely out of them when he died.
Now, of course there are differences between hit points and spell slots (for example, whether or not all characters have them), but the essential point I see here is this: if the argument for spell slots being restored or left as they were when the original creature died is because their presence or absence defines the characters' "abilities," then the argument is equally true for hit points, which also define a creatures' abilities by their presence or absence.
And as we've established, the cloned Wizard is copied based on their original at the time of its death, not from some earlier version. As such, it is very likely to have zero hp when it died.
The spell gives some guidance about resources connected to the creature's survivability, but this guidance is similarly unclear, or even contradictory. (e.g. that the spell is "a safeguard against death" implies the hit points return, but the fact that the copy is "phyiscally identical to the original" at the time of death implies they do not). Ultimately, the DM will have to make their own decision.
Now, the DM could come to conclusions other than restoring all of both, like declaring that the clone awakens with 0hp and no spell slots, but is stable. But the clone spell heavily implies that the cloned creature should awaken when the original creature's soul enters its body. Note that one of the options for the clone's container is a "mud- filled cyst in the ground, or crystal container filled with salt water." In short, some of the options for the container would be deadly to a breathing creature who was unconscious when they returned to life, which defeats most of the point of the spell.
As such, if a DM wants their rulings to be logically consistent, they likely will have to conclude that a Clone will have its spell slots restored if they want to have the clone's hit points similarly restored.
Sweet! So I get my spell slots back for sure, right?
The above relies on a DM needing to have their arguments be logically consistent. And the simple truth is, that's not something they're bound to. A DM will make the decision that makes the most sense to them, or that seems like the most fun. So they could definitely conclude that hit points and spell slots are to be treated differently by this spell, just because (Alan Mills makes an interesting point in their answer about how fully restoring spell slots could cause balance issues, for example).
However, without being able to know your DM's decision (which can override any explicitly written rule anyway), we will give advice on this site as best we can based on existing resources available to us, some of which are the rules and logic. And if we want these rules to be applied in a logically consistent way, then if hit points are restored by the Clone spell (and they almost certainly are), then spell slots will be similarly restored.