Yes. Reheating donuts is a common way to revive the fluffiness and softness of stored donuts. Warm the donuts in a microwave with a 5 to 15 seconds interval, but do not over reheat them, especially if they’re stored at room temperature. Donuts with melted icing are a bit messy to eat. Beware of donuts filled with cream or jelly as these fillings are hotter than you might expect.