Hello @torsten,
The best choice would be if you contact us to update your theme once you will notice Agama Pro v1.5.0 update available, since there are some things which will need to be updated manually.
We will do all procedure instead of you including backup theme files and settings.
You can anytime make own theme files/settings backup by plugins like:
https://wordpress.org/plugins/wp-all-backup/
But i can assure you that it would be best if you give us your website admin user/pass details in private reply and once update is released we will update theme on your website without any action needed from your side.
Best Regards