First, Yay! Characters should be adorable! :D Second, you're killing people in your story? You are awesome! That's not easy to do!
My suggestion and advice in this comes from years of running and being part of tabletop games. When it comes to re-killing everyone, or simply killing them, create another character known as "In-ebit-able". AKA inevitable. Inevitable has no emotions! Inevitable is all about making characters suffer. Then let Inevitable kill them. No sweat off your back and totally Inevitable's fault! :D