Do you transcribe other players' solos? I find this helps me a lot, especially when I transcribe non-guitarists' solos. The clichés and idioms on other instruments are simply different than they are on guitar, so that can help to see melody from a different perspective. Trumpets and saxophones, in particular, sit in a similar range to the guitar but have completely different styles of play.
To get the most out of transcribing solos, here are some points I think are important:
Choose solos you love, but from which you can learn. For example, I love the playing the blues and I want to expand my repertoire of blues ideas, but I don't transcribe Stevie Ray Vaughn solos. I love Stevie's playing, but I can't learn from it anymore. He played exactly what I would have played, if only I could play better. This is not to take anything away from Stevie, who did in fact play better than I do, but just to point out that I won't learn much from a Stevie solo that I don't already know.
On the other hand, I just transcribed Oliver Nelson's solo on "Stolen Moments", from his record Blues and the Abstract Truth (his solo starts at 4:14 and goes to about 5:54). "Stolen Moments" is also a blues, and Wikipedia describes his solo in it as "contain[ing] 'possibly the most famous' use of the augmented scale in jazz." I didn't know that at the time I started transcribing it (I just looked up the Wikipedia page as I was writing this), but I knew it was beautiful, lyrical, haunting, and entirely different from anything I would have thought of playing.
Get it right. Not just the notes, but the timing and the inflection as well. Get some software that slows music down without altering its pitch and allows you a great deal of scrubbing and looping control. I've used both the Amazing Slow Downer and Capo, and both are very good.
Getting the timing right is especially hard for me, but there's a lot to learn there. I have a tendency to overplay and to rush, and forcing myself to absolutely nail the timing on, say, a Miles Davis solo has taught me a lot about relaxing and staying in and behind the pocket. The inflection isn't as hard for me, but sometimes it's hard for my students. They don't seem to hear things like grace notes, slides, bends, vibrato, etc., the kinds of things that give the solo its vocal-like quality.
Write it down. This is important on so many levels. It will improve your reading, improve your knowledge of the fretboard, and it will really force you to grapple with the timing. Does that phrase really start on the 'and' of 3? How long is that pause? I thought those were sixteenth notes, but if they are, then the notes in this measure don't add up to four quarters. Hm.
Writing the solo out will also help with analysis. Once you've written it down, go back and write the chord symbols over the staff as they occur in the song. Then analyze the solo to see how the notes and phrases work with the chords. If you really want to go nuts with this, listen carefully to the chords that the other players are actually playing rather than the chords in the chart---they may be using alterations and substitutions, and the soloist may be playing off of those.
To be blunt: if you know the solo, write it down. If you can't write it down, you don't really know the solo.
Wisdom from Miles. Miles famously said about soloing, "Play what you hear, not what you know." In other words, when you're soloing, don't think about augmented scales and minor-7th arpeggios. Listen instead to what's in your heart and your head, and play that. Easier said than done, obviously, but this is exactly how transcribing helps the most: it trains your heart and head to hear ideas you wouldn't otherwise have, and it trains your fingers to execute better what you hear.