The correct way to upgrade within Windows 7 is to insert the higher version Product Key into Anytime Upgrade which unlocks in minutes the few extra (expensive) features almost no one needs.
Since Asus uses the Windows 7 F8 Advanced Boot Options
to trigger Factory Recovery, it is also wiped out with the OS.
The solution is to run Recovery Disks you should have made when you set up the laptop, order them from Asus Tech Support for a small fee, or get a superior Clean Reinstall - Factory OEM Windows 7
using the installer provided.
However if you own and want Ultimate on the PC it should work as well as Premium since they are the exact same OS and installer except for the few extra features. Are you using only the drivers given by Windows 7 installer and optional Updates, only importing any which are missing or problematic from the Asus SUpport Downloads webpage for your model?