I just added a new reload button when viewing the list of templates for a theme or plug-in. This will start downloading templates from GitHub again. It will update any existing templates or add new ones. (It does not delete templates that are missing from GitHub, so it still may be necessary to delete the theme or plug-in in some cases to force a full re-sync.)
The reload button will only show up if there is a GitHub URL set for the theme or plug-in.
