**Provide a side quest that gives the character/party options**

Instead of trying to somehow circumvent the save or die mechanic, why not have fun with it? If your use of save or die mechanics is at or near a point in the campaign where they can address it, and a rare occurance (hopefully), then an equally rare side-quest could be a great idea for your party.

You could ghostify the dead player (he'll get some neat new abilities and weaknesses), but the character should know that his ties to the mortal plane are *temporary* in order to provide urgency and discourage the player from keeping his character as a permanent ghost (unless you're ok with that). The character knows his energy and/or time is limited before he passes on.

Provide a plot seed that sends the party off to get their friend back, perhaps by eventually beseeching a powerful divine source or some other option and performing whatever tasks seem appropriate. Midway through, inject a morality fork that allows the player to be resurrected in a way that seems "easier" and more quickly by a power with more... *questionable* motives, with a potential reckoning to come later. Towards the end, I'd also try to inject a plot point from the main campaign to remind your players that the bigbad is still out there, and provide an opportunity for the ghost player to make an impact as a potential sacrifice by using up his remaining energy/time to deal a significant blow, perhaps in a way that a ghost could uniquely accomplish.

This allows the player/party to make one of three choices:

 1. Resurrect the player after a side quest with no other obvious side-effects
 2. Resurrect the player more quickly and more "easily" in the middle of the side quest with an unknown cost coming later
 3. The dead player could sacrifice his character's ghost by using up his resources/time on the mortal plane to further the campaign's plot in some very beneficial way, and then roll up a new character

Depending on the choices the party makes, it can reshape the story of your campaign. And it's way more fun than simply handing out "get out of death free" cards.