Microsoft will soon launch the new Windows 8.1 Preview, so all customers now running Windows 8 will be allowed to make the move to this version via the Windows Store.
In an interview with TechTarget, Erwin Visser, general manager of the Windows commercial division, explained that users should install Windows 8.1 though the built-in update option and not necessarily by performing a clean install.
Microsoft: You Won?t Need a Clean Install to Move to Windows 8.1