Pork shoulder is a big, flavorful cut of meat, and you'll likely have leftovers. To keep those leftovers safe, refrigerate them within two hours of serving at 40 degrees Fahrenheit or below. You can reheat individual plates of meat in the microwave for one to two minutes, but the oven works better for larger portions. Keep the meat covered and add some liquid so it doesn't dry out.
To reheat a whole barbecued pork shoulder, put it in an oven-safe roasting pan with a bit of mopping sauce, cider or water. Cover the pan with aluminum foil and reheat at 325 F for 30 to 40 minutes, or until it reaches an internal temperature of 160 F.
To reheat smaller portions, such as pulled pork or slices of barbecued pork shoulder, place the meat in a baking dish and pour a bit of mopping sauce or cider directly over the pork. Cover the dish with foil and reheat at 325 for 20 to 30 minutes, depending on the size of the pan. A meat thermometer inserted in the meat at the middle of the pan should read 160 F when done.