It's best to thaw the pork overnight in the fridge. You can reheat in a saucepan on the stove over medium-low heat until heated through. Or, in a preheated oven of 300°F in a casserole dish covered with aluminum foil until hot. For a large amount, put pulled pork in a slow cooker on the Warm setting for 2-3 hours or on Low for 1 - 1 ½ hours until hot. For any reheating method, add some chicken broth, apple juice, bbq sauce, soda or beer if the pork seems dry.