First check to make sure the hands aren’t rubbing on the face of the watch. Over time the oil in a watch gets gummy and that can slow it down. If the watch has not been cleaned in a few years then it will probably need to be taken apart, cleaned, put back together,oiled (with the proper oil), and then demagnatized. Check the mainspring to make sure it is producing enough power to the geartrain. If that doesn’t correct the problem then the balance wheel assembly needs to be looked at.