While I love the idea of WMI Filters, I am going to be honest: not many people use them. Chances are that you do not need to worry about backing up or restoring WMI Filters, because chances are that you do not utilize them in your Group Policy filtering. However, if you are one of the brave few that use this powerful capability, it is important to note that WMI Filters are not backed up or restored through the conventional GPO backup/restore processes. They are handled separately, and have their own wizards to walk through in order to back them up, or to restore those backups. Technically, what we are really doing is exporting and importing those filters.

Very similar to backing up GPOs, all you need to do is right-click on the WMI Filter that you want to save, and choose Export....

This generates a WMI Filter MOF files (*.mof) and all you need to do is choose a place to store this file, give it a name, and click Save:

The WMI Filter is now exported out to this file for safekeeping. In the event that you lose or mistakenly delete a WMI Filter from inside GPMC, the process for bringing it back is even easier. Right-click on the WMI Filters folder, and choose Import....

Select the MOF file that you want to import, and you will then have a chance to review the WMI query that resides inside this saved file. If everything looks good, click the Import button and this WMI Filter is now restored to Group Policy and ready to be used for filtering: