Start taking your time soloing and playing things you wouldn't normally play; start thinking about melodies, on and off your guitar. When you're not at your guitar try and hear a solo you'd like to play in your head, if you isolate a particular part of it and try to play it later the it's likely you'll be playing shapes and fingerings you wouldn't have thought of originally. This will also improve your phrasing for the same reason; as your fingers will instantly be trying to find new ways of phrasing things.
Start listening to some different music for inspiration?
Also, do you only improvise using scale shapes? I always agree with the: "Learn all the scale shapes and then forget them" quote, it's good to just be able to go anywhere on the neck without sticking to any shapes, to do this you'll obviously need to know the notes of your neck inside out.
Maybe concentrate on playing over a single chord, then variations of the chords with additions eg dominant 7ths, minor 9ths etc and concentrate on invidiual notes to investigate how each note of the chord complements the chord itself.
Good luck, we all go through down patches in our playing where we think we suck

I'm there now! lol