Updating your DEP token is required a year after upload, annually or if your DEP token is no longer valid, which can occur if you reset a password or when it expires.
You will:
Download an Orchard Public Key from Orchard
Upload this file to Apple
Download a Server Token from Apple
Upload the Server Token to Orchard
To Update your DEP credential:
If you have more than one DEP account, you may repeat the steps as needed.