I have a Samsung C series TV that was able to automatically refresh changes made in the minidlna server (media additions, deletions, etc). I appears that whenever a media directory is accessed on the TV, it reads the minidlna database; therefore it is always displaying updates.
The problem is that my new Samsung F TV seems to cache. It does not automatically pick up changes in minidlna. Haven't figured out how to make the TV refresh so I can see updates. I have to restart the server, the tv, or wait half hour or so.
Samsung's Link (dlna software) has a refresh button that triggers the refresh. It looks like it just re-sends SSDP requests.