Transcoder offers a way to retranscode media:

However, the functionality seems to fail when re-retranscoding, useful in cases where media files are replaced or if a job fails:
Unfortunately, Transcoder failed to transcode this file (see above)

The status page confirms the failure:

To do:
Investigate why Transcoder fails in this case, perhaps related to the verification logic checking the presence of an immutable variable that's set the first time a file is transcoded.
Ideally, Transcoder should push through all retranscode requests, no questions asked.

A good place to start might be the logic behind the Check Status button: