Just locate the closest port with an anchor on your map to where you are and set a course to it. Upon arrival to the port, you will be able to refit when prompt. Before leaving the port, go to your torpedo room. Move the torpedoes into the forward and aft tubes from storage, then click refit again in order to have a full load of fish! Now you are ready to continue your patrol. I hope this helps with your problem and answers the question that you had. Good hunting!
