Reading through the cleric spell list, it occurred to me that if the Life Domain cleric's Disciple of Life feature works on the regenerate spell, you would regain 10 hp instead of 1.
Is this valid?
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Whenever you use a spell of 1st level or higher to restore hit points to a creature, the creature regains additional hit points equal to 2 + the spell’s level.
Note that this not say once per spell or once per cast or similar wording, this bonus to healing occurs each time you are using a spell to restore hit points.
The regenerate spell description states:
For the duration of the spell, the target regains 1 hit point at the start of each of its turns (10 hit points each minute).
Since regenerate restores hit points at the start of the creature's turn, this means you are using a spell to restore health each time at the start of the creature's turn so this does change to 10 hit points each time. (Assuming you cast it using a 7th-level slot.)
There is a Sage Advice Compendium question that is similar to this, about the goodberry spell which also provides several instances of healing:
If I’m a cleric/druid with the Disciple of Life feature, does the goodberry spell benefit from the feature?
Yes. The Disciple of Life feature would make each berry restore 4 hit points, instead of 1, assuming you cast goodberry with a 1st-level spell slot.