There is no way to renew at the same discount that you signed up with. Any subscription you purchase will renew automatically at the full price. You can use a promo code to extend your membership by purchasing a new subscription while logged into your username. To take advantage of any current promotion, you will need to enter the code during checkout and apply it to the new order. The new subscription will not begin until your current subscription has ended. You will see a new renewal date reflected from your Account page.