According to this JetBrains documentation, you can easily include a previously excluded folder in your project:
To get an excluded file or folder involved in upload/download again
Select the file or folder to return to upload/download and choose Remove Path from Excluded on the context menu of the selection.
However, this has not worked for us (on several different computers & projects).
We are able to successfully remove it from the Excluded items, but it does not download the files.
We've tried:
I sorted the issue by going to 'Excluded Paths' tab in 'Deployment' window and removing from excluded also local representation of previously excluded remote path. I also needed to create that local local folder to be able to remove it from 'excluded paths' list.