I often make short ribs a day before serving. I find the taste just gets better. I also find that there is a lot of fat in short ribs. By refrigerating overnight, the oil will form a firm layer on top of the dish, making it easy for me to remove that excess fat the next day. Then, to reheat short ribs, I can either warm it on the stove over medium heat until the sauce is hot and bubbling and the meat is warmed through or put it in a 350 degree oven to heat through. I recommend bringing the pot of ribs to room temperature before reheating. This allows less time for heating and ensures the meat will get heated through in a shorter about of time. Watch your liquids and if necessary, you can add a little extra stock. Reheating can take 20-30 minutes.