Is your course plain with no modifications to components etc?

If so you should be able to just create a new course in the framework, switch the src-files and the theme and export.

Not using the Authoring tool myself so I am not sure what options are available there but as far as I know there is no export/import function of courses available yet. So I think, unless you are willing to reenter the course into the tool that this is your best bet.