From what many others have reported, many (possibly most) re-upload requests seem to be ignored, which is the uploader's right. If an uploader wants to keep his posts updated with active RG or NF links (when there's only a UG link left), that's great, but it should not be required [Login to see the link], which is a practice that I think could use some more thought.
Should a re-upload request be possible in this case? I think yes. Even though the chances are that it will not be re-uploaded, at least the uploader could be alerted that a link has died. It would be up to the uploader to decide if he still wants to keep the RG/NF link active. As long as the uploaders are not getting a high number of these types of requests, I don't see it as a burden. (I'm assuming there are already limitations on how many of these requests are permitted?)
Otherwise, if the re-upload request is ignored, or not fulfilled, then the primary options for downloaders (other than looking elsewhere) are: 1) make a request (here in the community), or 2) buy uploadgig premium (probably unlikely for most people).