Depending on how you read the spell, you may not actually have exactly five extra lives; you can theoretically be resurrected an unlimited number of times. It's just that after a few times it's so risky to the person casting the spell that you'd have to have several high-level clerics willing and/or coerced into laying down their lives for you to keep going.
The one part of the resurrection rules I would change is that in the fifth casting, I don't like that it only has a 50% chance to work. I think that if somebody is willing to definitely die to bring somebody back, then it should just work. How anticlimactic is it for somebody to decide that they're willing to do that, and then the coin toss comes up tails? (To date, the fifth-casting has never come up in any 13th Age game I've been a part of.) The resurrection rules are definitely way better than the D&D stabbed-in-the-wallet resurrection rules or other systems' death spiral of death rules, but if I was DMing and it ever came up, I'm pretty sure I'd let the fifth res just work. It's a major sacrifice, and it seems more satisfying if it actually works. (Not to mention it makes the option way more appealing.)
The one part of the resurrection rules I would change is that in the fifth casting, I don't like that it only has a 50% chance to work. I think that if somebody is willing to definitely die to bring somebody back, then it should just work. How anticlimactic is it for somebody to decide that they're willing to do that, and then the coin toss comes up tails? (To date, the fifth-casting has never come up in any 13th Age game I've been a part of.) The resurrection rules are definitely way better than the D&D stabbed-in-the-wallet resurrection rules or other systems' death spiral of death rules, but if I was DMing and it ever came up, I'm pretty sure I'd let the fifth res just work. It's a major sacrifice, and it seems more satisfying if it actually works. (Not to mention it makes the option way more appealing.)