This is very common because when playing fast, your fingers want to resort back to something familar. A good way to break this chain is to think melody before licks. If you force yourself into trying to come up with something melodic, you won't resort back to the same licks. If you listen to a solo, take Slash. He goes back and forth between fast licks, and melodic ideas all the time. That's pretty much the art of soloing, showing off your licks and tricks but also putting something melodic in too. Also, learn different styles of playing, pick up some jazz and maybe some classical. Both these styles emphasize melody and will also give you new licks. Shredding jazz licks in my opinion sounds really cool. :D It's a different throw from the standard, arps, and up and down scale shredding licks. Funk is also a good one if you want to mix up your rhythms.