Re-heating pizza can end in a soggy mess.
To avoid this, re-heat in a 400 degree oven on parchment paper. A pizza stone works great also, but requires too much time since it needs to pre-heat. A baking sheet also works, but it doesn’t take care of the moisture in the crust. When the baking sheet is lined with parchment paper, the parchment absorbs some of the moisture, resulting in the same crisp crust performed by a pizza stone.