Potato pancakes, also known as latkes, are rather temperamental food in terms of reheating. You can reheat them successfully --- that is, you can if you do so within a few hours of originally cooking them. They reheat better from frozen than from being refrigerated for more than a day or two, so if you do not plan to use your potato pancakes quickly, store them in the freezer until shortly before you wish to eat or serve them.
Preheat your oven to 350 F for fresh or refrigerated potato pancakes or 400 F for frozen potato pancakes. Place a baking rack onto a baking sheet.
Arrange the potato pancakes, either frozen or fresh, on the baking rack. The pancakes should not overlap or touch, but may be close together. If you cannot fit all of the potato pancakes onto the rack without letting them touch, reheat them in batches instead of all at once.
Place the baking sheet and rack holding the potato pancakes into your preheated oven. Bake them for approximately five minutes for fresh potato pancakes to 10 minutes for frozen potato pancakes. To check their doneness, insert a food thermometer into the center of one of the pancakes. They are ready to eat when they reach 165 F.