Very hard to offer you a custom answer. I found myself rather motivated to create new music rather than practising other's tunes. I still do it to be up to date with the repertoire of my two bands but that is just a part of my musical practise.

For me what I found very refreshing are Open Tunings that opens many new horizons for me to create my music pieces even if I don't play them I'm just very happy to create them I must have composed by now almost twenty of them. If you don't play with a band you can still have lot's of fun with a music software like Garage Band which offers you a custom drummer which I found very good to practise timing and develloping ideas.

Right now I'm exploring Double Dropped D tuning (DADGBD) which is frequently used by such as Doyle Bramhall II or Neil Young, it opens up new way of playing chords and tons of different riffs which take you away from repeating over and over the same damn licks of standard tuning