Save an old RPT-File in a new Version by command line?

Hello,

I have several (more than 100.000) RPT-Files which were generated in Crystal Reports Version 8.5.
Now I have Crystal Reports 2013 and I want to update those files to the new version or to open the rpt-file and save it as a pdf-file.

Is this possible by executing CRViewer.exe through command line or is there a VB.NET-Script which opens the file and saves it as a PDF-File?

Thanks for your answers!