I change things up constantly. I'll stick with a basic plan for a time, but within that plan things are never the same. For example, the order of the exercises, amount of rest between sets, DB vs. BB for a particular lift, etc.
The most important thing you may need to do is to examine your diet. Are you getting enough to eat to allow for growth? You may think you are, but keep up with your daily intake for a wk or so, and you may be able to pin point some of your problem.
Another thing, are you getting enough sleep? This is very important, because if you are being deprived of enough rest, you will be depriving yourself from good progress.