How do you know?
I would say if you are following all the "rules" from your surgeon as far as diet, exercise and mental attitude and you are continuing to gain weight then a revision may be in order. However you have to be honest with yourself as to if you are following those rules. You might journal your eating and exercise to see if it is actually what you think it is. It is very easy to think we are eating less and exercising more than we actually are so it helps to see it in writing.