Dealing with editors is one of the many joys we have as Umbraco developers.
There’s, to my knowledge, not much you can do except for educating the editors.
As for your case, it sounds like the preview feature is working as intended.
To help the editors understand what to do, I would instruct them to end their preview session, when they’re done.
This should clear the session data that tells Umbraco it should show preview content.
Working around this in code is probably not a route you want to go down.