So breath of life has the ability to bring back someone who died within the last round, but only if the healing provided cab bring it above that death line.
This spell cures 5d8 points of damage + 1 point per caster level (maximum +25). Unlike other spells that heal damage, breath of life can bring recently slain creatures back to life. If cast upon a creature that has died within 1 round, apply the healing from this spell to the creature. If the healed creature's hit point total is at a negative amount less than its Constitution score, it comes back to life and stabilizes at its new hit point total. If the creature's hit point total is at a negative amount equal to or greater than its Constitution score, the creature remains dead. Creatures brought back to life through breath of life gain a temporary negative level that lasts for 1 day. Creatures slain by death effects cannot be saved by breath of life. Like cure spells, breath of life deals damage to undead creatures rather than curing them, and cannot bring them back to life.
And a cure light wounds
When laying your hand upon a living creature, you channel positive energy that cures 1d8 points of damage +1 point per caster level (maximum +5). Since undead are powered by negative energy, this spell deals damage to them instead of curing their wounds. An undead creature can apply Spell Resistance, and can attempt a Will save to take half damage.
What I am wondering is if it would be possible to use both together in the event that you either rolled really badly for breath of life or there is that much damage? Naturally one of the spells would have to be quickened for this to work from the same caster.