When target creature dies this turn, return that card to the battlefield under its owner's control.
Graceful Reprieve can target a token creature, but since tokens cease to exist after they leave the battlefield, it won’t be returned to the battlefield.
Graceful Reprieve’s effect works only once. If the targeted creature leaves the battlefield and is then returned to the battlefield, it’s considered to be a new creature. If that new creature is put into a graveyard, it won’t come back a second time.