[Sirtel]

Another thing: if you only change the metadata, not the files themselves, there's no need to send the books to your Kobo again. Match the books to the library copies and set the metadata management to Automatic (Preferences - Sending books to device - Metadata management). Also, check the boxes for Update Metadata on the device and Update metadata on Book Details pages in the Kobo driver settings in Calibre (the third tab, Metadata, on device & advanced).

Now the metadata on your device should be updated automatically every time you connect your Kobo to Calibre.