the best way is never get into this kind of situation. but it is late now. ask yourself, are you a "fulltime" trader? if you are, the answer is obvious , cut the loss, now. wait for the next opportunity. if you are the normal person, having a normal job, you can do whatever you want to do. The normal person usually hold the losing position until they can not hold it.
If you have enough money reserve, I think it's ok to hold the short positions. But as long as you don't know why you are wrong, don't add more positions...
it depends on your balance size. I knew that a big cow shorted one stock in year 2000 and kept shorting it for several years until it came back. However, its account was over billion.