If no one else has placed a hold on your title, and your library has enabled renewing, you can renew your title within the mobile app. The Renew button will appear once a renewal threshold (set by your library) has been met.
1. Tap the Renew button.
2. Confirm that you do wish to renew your title by extending your checkout period.
3. You will receive a confirmation message, stating that the renewal was successful and providing your new expiration date. Tap Keep Browsing to continue browsing your library's collection.
Note: Although the above screenshots are for the Android version of the app, the process works the same for your Kindle or iOS app.