There aren't many modifiers specifically for Extra Life and Extra Life alone, but two do exist.
- GURPS Reign of Steel: Will to Live (pg. 19) provides Brain Pod, for your jarred brains or AI cores that can survive their body's destruction; unsurprisingly, it has to be taken in tandem with Requires Body.
- GURPS Zombies (pg. 52) has the Reanimation modifier, which guarantees you'll rise as an undead.
I've never used Brain Pod, but Reanimation has proven useful for some Sorcery spells designed to reflect rituals that guarantee immortality at a price.