We often have a few pizzas left over after an oven session and I've developed a bit of a technique to reheat them sucessfully. Obviously, you can put them in the tinger, but you risk soggy rubber, or you can put them in the oven, which works, but is expensive on the juice, unless you are cooking something else.
So here goes:
If freezing the pizzas, freeze as soon as poss once cool
Freeze in a well sealed plastic bag, eg a ziploc bag
Even if storing in the fridge for a day or two, still store in a sealed bag
Prior to reheating, defrost, preferably in the fridge to defrost slowly and save a bit of energy
You now need a big frying pan and a lid; the frying pan should be a heavy gauge one, preferably one of those deep, cast aluminium, non-stick saute pan style ones. It needs to be big enough for the pizza to sit flat on the bottom. The lid doesn't have to match, as long as it seals the top of the pan properly
Put the pizza in the pan and put the lid on
Reheat using a low flame until the mozzarella starts to bubble and remelt
Reheating this way, the pizza will taste almost as good as it did straight out of the WFO!