We are wondering if there is a way to prevent a student from accessing a course that they are currently re-taking so the student cannot go back to the older course and see any information.
Are these two separate course shells? If so, you should be able to set the student's enrollment in the older course to be "Inactive": https://community.canvaslms.com/t5/Instructor-Guide/How-do-I-deactivate-an-enrollment-in-a-course/ta...
Just go into the Settings for the old course. You can set the date after which students can no longer access your course. (You'll still have access to your old course.)