New Game+, but with a fun twist!

After some special means of activation during post-game (maybe a method to make the core produce a beacon signal?), Urschleim will change its route and begin a spiral path until it reaches the core. If the players don't defeat it enroute, (maybe also with unique drops or some new gimmick for challenge?), upon reaching the core, the core deactivates (as if to reset it to the its state at the start of the game), thus requiring all of the bosses to be defeated all over again as if from the start. However, they're now "Urschleim flavored", which works out to be a "new game+" effect with increased stats and new behaviors to match end game-level players.

Might also be neat to have "urschleim" biomes, buffing mobs and adding new visuals (or even loot). Think regular biomes, but covered in urschleim goop (urschlime?).