You can update your offer for a product through the Manage Inventory page.
Go to Manage Inventory.
Click the Edit button to the right of the product offer you want to update. This will take you to the Edit Product Info page. On the Offer tab, you can update the following fields:
Additional fields are available depending on the following:
When you have edited the fields for your offer, click the Save and finish button.
Your offer will update on Amazon within 15 minutes. In case of maximum load on Amazon systems, it can take up to 24 hours for offer information and 48 hours for product information.