Fuscias in Pots

I have several hardy Fuscias which have lived in the same outdoor pots for years with very little attention save cutting back when i see new signs of life.Just wondering if taking them out of the pots,if i can ,and trimming back some of the roots whilst still dormant is a good idea.Then perhaps repotting with J.I.No 2 or something similiar.

They do flower each year ,but not as prolific as years previous.Any one done this ?