You can go manage your Kindle content at http://amazon.com/MYKupdate. When you log into your Amazon account, you will see a list of titles on your Kindle.
From this list, you can access information about each title including cover art, purchase date, the amount paid for it and other order details. Also, the action menu on the right side of the screeen gives you access to tools for managing your Kindle content.
Content that has been updated will be marked with “Update Available”. To make life even easier, you can filter your Kindle content to show only the content that has been updated. To get the updated content, you can use the Action menu on the right hand side of the screen to have it delivered to your Kindle devices. For ebooks, you can also click the “Update Available” link.
This is a change from the old days. In the past, you had to go through customer service to get updated content for Kindle. The process is now much easier and more streamlined.