Pro/Batch can perform the update.

Use Pro_batch with the Upgrade option selected for all the files.

But specify the file that you want it to use, or run it from a directory that has the right

And set these config options (you may choose different settings):

 save_model_display        shading_lod

 save_drawing_picture_file        embed

Use Pro/Batch to convert at night.

Batch open and save all of them with the proper config options set.  There has been some traffic on the exploder about batch processing files so I'd check the archives.  If you can't find it there, I might be able to make some suggestions.