I go through the same things, not only in art, but in life as well. Its a natural cycle like working and sleeping. The way I approach it is to work on techniques and just play with buttons during the dry spells to see what happens with the program (or go back to school when the job is boring and I want a change) and use that time to learn. Rarely do I come up with art when in the learning phase, but always I come out of it and am better off for it. My last dry spell ended when I got Poser which brough a new dimension to Brycing. Certainly the monthly challenges help with dry spells too because the question of "what to do next" is answered by the challenger.