Scott--I feel your pain.
Several of my listings failed to post. I had made many revisions to those listings, especially adding custom features.
When they fail to post, the entire listing needs to be reworked with all the changes that were previously made and it has to be done from the saved listing tab.
The links on the scheduled listing tab to "edit and reschedule" don't work, so there is no change of just relisting with all the changes.
This is true whether there is an API error or a "failed to post" error.