One way to almost immediatley get out of the rut is to play along or in the style of music you don't usually play. Like classical, jazz, or regae for instance. Even if you don't even particularly care for a style of music, learning how to play in it will transfer to improvement in yer main styles of playing.

However probably the best way to vastly improve your creativity and abilities is to jam with other people. You've been playing 3 years...so start a band, or even just a weekly get-together of some friends who play something. I had played for about 3 years when I started jamming with friends in high school. I surprised myself at my progress. Now that I'm more solo again, it's harder to stay out of the rut.