A bit of a repetition of what's been posted already, but here, from "The Advancing Guitarist", are Mick Goodrick's thoughts on the subject:
~ Play on the tunes that you are currently playing, but at least twice as slow. (And no double time!) This way, if you start to play any of your "pet licks", it will sound so bad to you that you'll probably stop right in the middle and quite possibly actually start to imporvise, since, at the slower tempo, you'll have much more time (and space) to think/hear/feel other kinds of ideas.
~ Ask yourself: "Is there anything really important in music that I've forgotten about?"
~ Feed a loaf (or two) of bread to some pigeons, ducks, sea gulls, or other types of birds.
~ Imagine a time or circumstance where you could never play the guitar again.
~ Go for a long walk.
~ Cry.
~ Stop playing the guitar and/or listening to music for 1, 2, 3, 4, 5, 6, or 7 days.
~ Stop playing the guitar, but listen to a lot of music for 1, 2, 3, 4, 5, 6, or 7 days.
~ Change the strings on your guitar and polish it.
~ Send your guitar "back to the factory" to either be retuned or recycled.