Are you in a band? I find bouncing ideas off other musicians makes me more inspired than anything I can do alone.
Also, other styles, different gear (especially different effects), even a different tuning, all of them will give a burst of inspiration. I found getting my POD HD500 made me come up with a lot of new ideas for existing songs to make them a bit better, as well as bringing a few new ideas too. I'm also running Drop A on one of my guitars now and finding new riffs all the time because of it.
It depends on what your regimen has been up to now too. If you've been solidly practising technique, start having some fun. If you have been doing nothing but writing/having fun, maybe time to add something new to your arsenal/repertoire?
Just a few ideas to play with anyway.