For my long rides, I'll put the bike in the van and drive to different corners of the state, or even a bordering state (live in Connecticut, so small in area). That gives me a lot of variety - and, in New England, there are a lot of variations you can put together, especially if you are set up to do gravel, too. I'll drive up to an hour and a half to start my rides and that gives me access to beautiful routes throughout Connecticut, and into New York, Massachusetts, and even southern Vermont (I'll ride sections of the D2R2 gravel courses when my legs are up to it!). Not sure if that approach would work for you and, admittedly, 2-3 hours of round trip driving along with a 4-5 hour ride does take up the better part of a day but it works for me.
For my shorter rides from my house, I've got some variations but it can get repetitious. One of the routes includes a nice hill climb that has a fair number of walkers (there are hiking trails to the top in addition to the road) and some cyclists. At the top, there's a view point and often I'll chat with another rider or walker. So, while the ride isn't 'new', I find chance meetings with other people another fun aspect to cycling that makes it interesting.