You can, but I would only reheat leftovers. The belly is otherwise best served immediately for maximum crispiness and juiciness. Oven: You can reheat a whole piece or just the leftover slices. I have the slices most of the time, and they take only minutes to reheat at about 200 degrees Celsius/ 400 degrees Fahrenheit. Pan: frying the sliced meat in the pan goes even faster than the oven method. Air fryer: it only takes a few minutes for the slices to get hot.