I'm not 100% if ErsatzTV auto scans libraries. I do not believe so. Best way to make sure new content gets scanned is to go into the library and do a deepscan.
Other than that, it depends on how you are creating your broadcast. If you're throwing all your shows in a single collection and then telling ersatz to flood the broadcast with everything in that collection randomly then you will have to add the new shows you get to that collection manually everytime. No way around it.
If you have a set schedule that you created, then you will have to insert that show into your schedule.
If you're using blocks then you'll have to add it to the block.
It all depends on how you set ersatz up to run your broadcast and how you prefer to have your broadcast organized.