That should be as easy as go to the BIOS and enable the watchdog again, now if the WDT were actually uninstall you may need to check with Original equipment manufacturer (OEM) (ASUS* )to get proper and customized drivers for your system or further information on how to fix this inconvenience.
Did you check if the WDT is enable it on the BIOS?
I do understand your concern, but the watchdog timer is a BIOS feature and normally is just a matter of enable or disables it on the BIOS and if it needs a update from one version to another it might be through a BIOS update. On the Intel site you can find generic drivers for the 6 series chipset for desktop boards, but not drivers for WDT feature. The Original equipment manufacturer (OEM) should be able to provide you with a straight answer on this matter.
In my case, reinstalling ASUS AI Suite II also reinstalled "Intel® Watchdog Timer Driver (Intel® WDT)".
The "standalone" install is at "<ASUS AI Suite II Install folder>\TurboV EVO\AppSetup\ICCWDTInstall\", if you want to install only this missed component.
Hope it helps