Before I save my map I rename the folder appending _bak at the end. This prevents the folder from being deleted. Then I save the map. Then I open the map in a web browser so MapGuide will create the tile cache folder.
Then I open the _bak folder and cut/past its contents into the newly created folder.
I rename the folder where the tilecache is saved (basemap to basemap1) before I save my map definition, then save, and then change the folder name back to original (basemap1 to basemap). No need to cut/paste folder or files.