Since you have a spellcaster, you don't really have any need for ambrosia.
Potion of Prompt Resurrection- Drink this BEFORE you do something sketchy, such as continuing your climb up the mountain after you've gotten hurt. It does fail a lot, but when it succeeds, if you die you just get right back up again. This does have to be drunk BEFORE something happens, if you die it's too late to try to drink it.
Potion of Rejuvenation- Will reset your days in current age span to day 1, just like a Potion of Youth.
De-Deathify spell- turns a ghost into a living sim. Which is what Ambrosia does, but you don't need ingredients or anything.
Now, if your other sims aren't spellcasters, they aren't going to be able to use magical means to bring back your spellcaster, and maybe they SHOULD have Death Flowers and or Ambrosia handy. Or if somebody's a writer, bind a Book of Life to them. Potions and spells can be given to/cast on a non-spellcaster though.