https://www.strava.com/heatmap
Mix up the intensity. Intervals, recovery rides, tempo rides, longer rides, shorter rides.
Strap some camping gear on your bike and do an overnighter out-and-back. Or stay in a hotel at the overnight if that's more your style.
Get a second bike that's a different type. Cruiser or fixie or recumbent or velomobile or anything. Or a tandem if you can find a partner.
If the roads are lightly traveled, night riding can be amazing. With the right lighting, of course.
Take a camera along, stop every five miles or so.