Hey just saw this...

Just use the "Upload" button, not the "Upload as New." This will update the same file in the Workshop, which you can verify before uploading by clicking the Workshop name link at the bottom of the Level Tab.

As long as you are working with the same local file that you uploaded, OR a local copy of it after uploading, then this will work. However, there is no way to manually link a completely different local file to a Workshop level.

"Upload as New" creates a completely new Workshop file and links the local file to it.

Does that help clarify? In a future update, I'll have the button text change to "Update" to make it more clear for everyone :)

Thanks for the reply! Well what I did was after I edited my level I accidentally uploaded a new one instead of updating it, so whenever I try to update now it updates the new one I uploaded. Can I switch it back to update the original?

Sorry, once you upload a local file it's forever linked to that Workshop level.