I have he same thing as you OP. Still using the map I set up at my start a month or so after game release... still not explored it all (OK I may be slow but why rush?) You'll find some have no doubt!

The "Upgrade World" mode has been my go to after every release of content and it does it exactly what it says on the tin. In fact considering using it to reset & refresh my world (bar the buildings) and inviting friends over ;)