Updated a topic in a course, need LMS to track completion only for this particular topic

Here's the scenario:

We created a course, published it as a SCORM, and then uploaded it to an LMS. Many students have completed this course, but then we have received a piece of new information that needs to be added to it. Let's say that we need to edit or update 1 sub-topic out of 10 sub-topics, which is Topic 3.

We want the LMS to reset the completion percentage from 100% percent to 90% (or from "Complete" to "Not complete") until the student has completed Topic 3 without having to redo the entire course.

Can anyone give me some good tips on how to go about doing this?

Thank you.