Q: Say you upload a whole 10k set ahead of time then realize that you messed one up and want to fix the arweave data. Are you hosed, and just have to re-upload everything with a new CM?
A:
Go to the temp file created by CM.
Find the one is broken.
Change arweave URL to new one which is not broken.
Mark on-chain: true -> false.
Re-run the upload
command.
Upload command will find the one is missing and reupload it.
That's it.