How to: Perform a Repair Upgrade Using the Windows 10 ISO file
Try an in-place upgrade or repair upgrade and choose to keep your personal files and apps. This will completely refresh Windows without deleting any of your personal files or programs you downloaded.
I just performed one a few days ago on a work computer and it takes anywhere from 20 minutes to an hour, dependent on your internet speed, needed updates, and the speed of your computer.
