All the above suggestions are great, and I would emphasize finger picking. There are a lot of different picking styles. I have never gotten used to a pick, I prefer the feel of the strings. Different picking techniques can add zest to a worn-out song, by changing the way yopu think of the song. You can change the tempo, go from 4/4 time to 3/4 time.
Also, do you compose? Try coming up with your own unique chord patterns and then see if you can combine several into a fresh new song. And while you are at it, try different ways to play an old chord: I use a lot of D variations: xx0232, x40230, x30030, x20030, x10030 the left-most number for each group represents the left-most or bass sttring and the right most number of each group represents the high E string. The numbers are the frets you play (x = muted, do not play).