SOLVED: How To FORCE Windows 8 (or 8.1 Preview) to Update to Windows 8.1 Release

If you have run your Windows Updates but still do not see UPGRADE TO WINDOWS 8.1 in the STORE APP, try launching Internet Explorer app and type:  ms-windows-store:WindowsUpgrade into the address bar.

For more details expand the first twisty on http://windows.microsoft.com/en-ca/windows-8/update-from-preview .