Heya @rombizio
Ah, yeah that’ll be in the world rather than on the assets library.
What you want to do is export a backup of your world (explained here if you get stuck, but you can essentially go to the game configuration page and Export World on the top right Game Tools section).
You want to put that world into your local FoundryVTT data folder under worlds (%LocalAppData%/FoundryVTT/Data/worlds on Windows). Your original world will be in there and you want to replace that with the more recent one (replace, not merge folders). I recommend you cut the original out and zip it up so you have a backup of your original.
Then you can restart Foundry, and it’ll have the latest stuff that you had added back on Forge. Bear in mind, you might need to update modules and stuff locally to the versions you want, modules and module configs don’t get exported along the world since they’re stored separately. But macros, actors, tokens, etc. do.