Downloading Latest Version

When downloading newest version how do I keep all of the updates from a previous version so I do not have to download all the updates again, which takes a very long time. I am hoping that there is a way to import or copy the existing update files over to the new version to shorten the complete download cycle of updategenerator on a new WSUSoffine version. If anyone has accomplished this and has a procedure your guidance would be very much appreciated.