Changes made to iBooks for Mac not syncing to iBooks for iOS

I have added a number of books acquired from other sources (both epub and PDF) to my iBooks for Mac application and synced them to my iPad. But when I make a change--such as amending the title, or adding author information--on the Mac, this information is not being synced to the iPad for some reason, and nothing I do seems to be able to force an update. I suppose I could delete the books affected from the iPad and resync them, but there's quite a few of them and if I can avoid that sort of tedious work I would.