Want to have warm leftover pizza in minutes?
Put your pizza slices in your toaster oven and TOAST THEM!
The cheese will melt and get stringy again and may drip if you put it directly on the rack. Personally, I try not to let anything drip to the bottom of my toaster oven, but that's just preference.
I've been using this trick for years now. I hope this helps you enjoy your leftover pizza with less hassle! ENJOY!