Huh, you can try to load data of your old version and put it into the new version with WinMPQ and try if that helps. Don't forget to make backups.
(Everytime I open my best project I click on a bat file, which runs JNGP and then Backups my map, BEFORE opening it in JNGP. Everytime the filename has 1 count more and so I have a full list of all of my updates. I have about 400 versions of my Arena. Every single time I open WE I will make a backup. That rocks )