Adding to what Shobet already mentioned; why not actually do something very different on the guitar for a while ? If you are a Blueser - go off on a Jazz detour for a while, or Metal / hard Rocker, some Classic / Neo Classical specialisation for a bit. If you already do both /all / delete where applicable - then how about brushing up on whatever theory might come in useful, - or just learning / re-learning / revising arpeggios and such, and running them on the guitar, whilst watching Television. A great way to induce subliminal learning - and get that sort 'under your fingers'.
It ALL eventually bleeds back into whatever your original stuff was, and makes the 'tool box' bigger.
I also find going to whatever 'other' hobby you have for a while works a treat, especially if it is ( for example ) more physical, or certainly less cerebral. If in doubt ( as Shobet implied ) - just put it all down, and stick it back under the bed for a while. I have always found that the 'block' clears - and in fact, you somehow come back much better at whatever you already did - without trying.
Pardon the expression, but the pragmatic name for this sort of thing is " Brain shag ". :)
