here's how I avoid a rut

1. I don't buy wood (well, very very very rarely)
2. I don't generally start with "clean" wood cut to a round "blank", instead
I start with a gnarly thing with branches and holes and bark and worms and
whatever else nature gave it.
3. I spin it up and remove all that doesn't belong. Each time I get a
different result. sometimes the result is just dust and scrap, sometimes it
is a "clean up the shop" event, but if the result exits the lathe with
finish on it and in one piece, it is definately not a copy of whatever I did
before.

root balls are good for this (pick ones small enough for your lathe) - use
plastic (pourable, clear) to fill in gaps and make it hold together (I'm
still working on one of these) - goblets from fresh wood that moves a lot
(eucalyptus is interesting), you get the idea