Hi Greg,
You can convert your AS2013 files directly to AS2015. You do this in the Management Tools. After, select the "Convert Database", then in the top left corner go and select the "open database" and select all the files you wish to convert. Click on "convert all".
If you are experiencing difficulties with these steps please call support or write us at: Graitec Tech Support <support.americas@graitec.com>
Regards