When you reheat a baked potato, it usually will not be as good as when it's first baked. That's why I fry mine the second time around. If you put it in the oven, it will dry out. You can wrap it in a damp paper towel and put in the microwave for two minutes. It will come out moist and will taste good, but it won't be quite as good as when you first made it. But, put butter, salt, pepper and sour cream (and chives if you have them!) and you will still enjoy it, and get your vitamin C.