The best way to reheat a fully cooked ham is by slowly reheating it in the oven. This method maintains the ham's moisture and preserves its flavor. Start by preheating the oven to 325°F and placing the ham in a shallow baking pan. Cover the ham with aluminum foil, and bake for about 10 minutes per pound. Test the internal temperature before serving to make sure it has reached an internal temperature of at least 140°F. For added flavor, brush the ham with a glaze of honey, orange juice, and spices before reheating.