It is also recommended to take a snapshot before you start the below process. If something fails, you can revert to the old vm from the snapshot.

1. Boot your original master VM up.
2. Install the new application
3. Shut the VM down
4. Take a new snapshot of the VM
5. In DesktopStudio select the catalog in the MAchine node and chose “Update Machine”.
6. Select the new snapshot and the image will be updated.

I even tried to update the VM without taking the snapshot, but using an snapshot to update VM is the best practice.