These courses require a valid certificate at the time of the course start date and re-certify you for an extra 3 years in the same course and level.
There are only 2 types of courses that can be re-certified: Standard First Aid & CPR, and CPR/AED Only
Re-certification is allowed only once. If a re-certification is currently held, and about to expire, than the full course is needed. Full courses can be found by clicking this link