The bas modules  are stored internally, so you'd need to use VBA itself to
manipulate the modules programmatically. This could be done, but would take
quite a bit of work to set up. (You can import the bas modules yourself by
simple drag and drop from one sheet to the other in the VBA environment.)

An alternative is to put the software into a .xla file. You can then link to
the production or test  one as required. In particular, you can replace the
production one by overwriting it, and people will automatically start using the
new one.