I already completed this training, do I need to take this course again?

Any time an activity is completed and needs to be retaken (or re-certified) the latest user's attempt will appear on the activity details page. The training status will indicate “Attended” with the previous score. The user will need to REGISTER Again, launch the course again and click the RETAKE button to re-certify. Additional language was added to let users know they are expiring soon (for certifications) with language to retake the activity again. In short, yes, users need to take the course again and make sure they are clicking the RETAKE button to record a new completion in their transcript. Restarting a course will NOT wipe any previous completion history. Users could also verity when they've last completed the course by clicking on the Attempt History. 

Examples for courses which require re-certification: 

The Compliance Training page lists courses, the frequency of recertification, and their estimated duration.