Perhaps learning to play the melody and then palying through various permutations could be a start?
Learning other people's solos and lines, and then trying to adapt those, can also help develop your vocabulary.
Singing over the chord progression, then attempting to work out what notes you have sung can be a good way to develop your soloing as well.
I would also say that you could get a lot from
Plane Talk in developing your soloing. It is an excellent resource.