Restricted Navigation and Free Navigation

Hi all, I think my situation might fit within this discussion (otherwise I will create a new one).

We have a course hosted on an LMS. It is currently in restricted navigation.

We want users to gain free access to the training upon completion so that they can revisit it freely.

My issue is that we update the training twice a year and we would like trainees who completed an earlier version of the training to be able to access the new content freely. Even whole new modules.

Is there a way to do this? Currently we have 2 versions of the training online. Upon completion of the original you gain access to a new training called "open version"  which has free navigation.

This works but we would rather have only 1 copy of each training rather than 2. Is there anything I can do?

Thanks in advance.