Atmel Studio will automatically upgrade the tool's firmware when needed. A potential firmware upgrade is triggered once you start using a tool. Examples: the first time you launch a debug session or the first time you select the tool in the Device Programming dialog.
The tool cannot be used by Atmel Studio if the user chooses not to upgrade.
You can also check for firmware upgrades by using the Available Tools view (View → Available Atmel Tools). Right click on a tool and select Upgrade.
For a description on how to do a manual upgrade, downgrade, and upgrade with a custom firmware image, see Manual Upgrade.