Click the "Subscriptions" tab (yellow arrow below).Under "Inactive subscriptions" click the arrow next to the product you want to reactivate (pink arrow below).Click "Re-activate" (green arrow below), then click it again in the sidebar to confirm.Update item information as needed:  Quantity (orange arrow below), Next order date (purple arrow), Order frequency (black arrow), and Shipping & billing pair (gray arrow).Follow the prompts in the sidebars to complete the specific updates.