French toast can be reheated in the microwave pretty easily, right from being in the fridge of freezer, but it won't have a crispy texture. Just put a damp paper towel over the french toast and heat it up for 20 seconds at a time, until it get the desired temperature. You can also re-heat it on the stove or in an oven, but you need to thaw it first, if frozen. Just take it out of the freezer the night before and put it in the fridge. Put it on a baking sheet if heating up in the oven. If heating up on the stove, heat up a nonstick skillet with some vegan butter or coconut oil on medium heat. Heat for a couple of minutes on each side. You can use a toaster oven or toaster to heat up french toast as well.