How to update Group policy for the whole domain

That's not a very sound recovery strategy. You cannot simply re-create the same naming and expect things to work. Every object in AD has a security identifier (SID). Creating a lot of objects with the same names might look the same to you, but to AD they are all completely different because the SIDs will differ.

You should look into the proper way to backup and restore Active Directory, this simply isn't the way it's done.

"Import" is accomplished by copying the admx/adml files to %systemroot%\PolicyDefinitions folder (the default location) where you will run Group Policy Management Console. The .adml files are copied to %systemroot%\PolicyDefinitions\xx-xx, where xx-xx is the language code.

Or if you use a Group Policy Central Store, %systemroot%\SYSVOL\[domain]\Policies\PolicyDefinitions on one of your domain controllers, where it will be replicated to the other domain controllers in your domain. If you have a domain that was upgraded from 2003, the SYSVOL directory may be SYSVOL_DFSR.

https://blogs.technet.microsoft.com/askpfeplat/2011/12/12/how-to-implement-the-central-store-for-group-policy-admin-templates-completely-hint-remove-those-adm-files/