External document generator need to trigger refresh in PowerPoint

I am developing a generator for PowerPoint presentations.
At the end of a generation cycle, the output file should be shown in PowerPoint.
Just opening the file therein is not sufficient since a previous version of the file may already be open;
that would then need to be closed first.

This action should be triggered from a Scala program, which runs on a JVM.
The solution should not require running an MS Office macro (such as given here).
We may assume the file is not being edited in PowerPoint; there will be an option to generate it as read only.

I need solutions for Windows and Macintosh. 
I have experimented with AppleScript from the Mac Script Editor, but I only manage to 
have PowerPoint open a file when no file with the same name is open yet.
So I would appreciate help.

Andre, I'm sorry but that sounds too advanced for me to be able to help you out. I do wish you the best of luck and hope you find a solution soon.