I still think it should at most be a one time thing per match, a "Oh Crap" button so to speak.
If you manage to get your self backed into such a corner that you can't spawn, then use the invincibility to make a push. If you somehow manage to get pushed to your spawn again, then you simply deserve to lose that match because you were out played.
3 lives is way too often in the game mode considering how frequently people die.
I think one per person per match would suffice just fine, just like how the jetpack should be.
