Zen and the Art of Dying by Jared Wynn

Kenny has two problems. First, he’s a Reset, which means that whenever someone murders him, he wakes up on the morning of his dying day to start all over again. Which might sound like a pretty awesome superpower, but it’s actually super sucky because he’ll eventually die of cancer or old age, after which point he'll just keep reliving his agonizing dying day forever.

His second problem is people keep murdering him.

So he teams up with another Reset and they storm the lab where it all began in an effort to undo this unordinary death disorder. They keep dying, they keep trying, and then they keep resetting and relaunching their attack until they almost succeed. But then the girl Kenny fell in love with gets kidnapped, and then his partner gets kidnapped, and then pretty much everyone else gets kidnapped, leaving Kenny all alone with his thoughts and a nagging question that just won’t die: what’s left to save when everyone and everything you know is gone?