Usually I like to start a new project from scratch. Reworking pieces that I have previously made is always difficult and a little less satisfying than creating a whole new piece of work.
If you make things by hand for a long time, you inevitably end up with a growing collection of odds and ends lying around. These can be from experiments that did not work out, or were abandoned, or even finished works never sold and you were never completely satisfied with. Once in a while I make an effort to use some of these pieces to develop new work and I recently produced a number of things that I am quite pleased with.