Excessive watch battery drain after a phone upgrade

Every time I do a phone upgrade, my Apple Watch battery starts draining at a ridiculous rate. I did the most recent upgrade one week ago and I have unpaired and repaired the watch several times and it is still draining to zero after about two hours. I know from previous experience that this is a software issue not a hardware issue. My watch is two years old. What can I do? At this point I can’t wear the watch at all.