How To Batch Update Album Art

I am a new mp3tag user and I've tried searching for an answer to this question without success...

I have an existing folder.jpg file in each of my album folders to represent my album coverart. Unfortunately most of them are fairly low resolution and poor overall quality. I experimented today with mp3tag's abilty to add coverart to each song by doing Tag Sources/Coverart/ These .jpg files are typically 500x500 which is 4 times as good as the resolution of my current folder.jpg files.

However, this process is manual and doesn't update the folder.jpg file. Rather it creates a separate metadata folder with a .jpg file for each song which is fine. But my question is, is there a way to select my entire library and have it replace my existing folder.jpg files?

Unfortunately, batch processing anything to do with data/file retrieval from the web appears to be something Florian refuses to entertain.

That's unfortunate and would really round out a very nice tool. Thanks for your reply.