If you have already downloaded a new Keplerian element file, you can use Nova for Windows' drag-and-drop to update its internal satellite database.

Simply drag the file, whatever its name is, from its current location to anywhere within the Nova for Windows program or its icon on the Windows desktop:  

If the file contains valid Keplerian elements (AMSAT or NASA format), Nova will read the file and update itself.  If the elements cannot be read, then you will receive a message informing you of that fact.