There is a theory on John Haririson's book redefing stuttering (i suggest to everyone in here to read it) that is called stuttering hexagon. The theory says that there are six points on the hexagon: Physiological responses, intentions, beliefs, behaviors, Emotions, perceptions and what makes the Hexagon able to support itself is that, functionally, all points interact with all other points. So when you are doing stuff to build your confidence and keep pushing your self to stop avoiding situations, your hexagon would be more supportive and you will keep your fluency. But here is the trick, if you gain fluency and you are happy with your speech you have to push your self doing things to keep your confidence because your old behaviour will come back.