mapmerry - this goes back to the last stable, but not the previous beta. I saved my project at 159...I'm screwed until the next beta release, aren't I? :)
If you want to try some hackery (make backup of the game files first), it's possible to manually edit the .caproj file so that Construct tires to load newer version files..
Close a top of file there shoudl be line like
... Try if the version number change would help.