Re-generate world as a Biomes O' Plenty world

Solution 1:

I ended up doing Marco Geertsma's idea. Here's what I did

1. Stored everything I had
2. Logged off
3. When into my players folder, and backed up {YourUsername}.dat
4. Regenerated my world
5. Logged in without restoring my character so I could get the coords for world spawn, as the .dat file seemed to contain my coords too.
6. Replaced the .dat file with my backup
7. Logged in and teleported to the world spawn coords.
8. Rebuilt my house, and off I go!

I also used a different world seed, but you could easily just keep it the same.

Something I cheated at to make it easier for me, was I got a couple of Strongboxes to store all my items, and I could only carry about a third of my items at once.