The books will need to be resent as Calibre has no auto-sync capabilities.
I am not sure with the Kobo if you need to first delete the books. Some readers have a tendency to cache data about books and so do not notice a resend. I am not sure if the Kobo falls into this category.
You might find it useful to look into the
Reading List plugin. I find it useful to maintain a list of books that I later need to sync to my device as I can add them to the list without the device being connected. In your case this could be at the point where you amend a book.