Try playing songs differently each time. Our tendency is to learn a song cold and do it that way all the time. Get someplace alone and try out some real differences...see Norton1 above. If its fast, do it slow. Try making it real bluesy. Capo up five frets. Once you are comfortable with big changes, play for people as much as possible. I use Paltalk to accomplish this. Folks there are generally appreciative, and many comment on liking to hear a familiar song done very differently. Keeps it all fresh.

dw