Hey there,

instead of migrating your old world, you can treat new worlds as 'expeditions' instead to explore new content like the caves. Items can come back with you in the inventory, and newly unlocked recipes are tied to your character. Crafting stations in your old world are currently able to work with new items, even if that world hasn't been able to generate (for example) ice caves itself. Fingers crossed that it will stay that way with new biomes as well.

Hope it works out for you!