I am quite new to oVirt and only use it at home for the moment. So I wont be of much help.
But I was able to add a new export domain, and then copy the original contents of my old domain into this export domain, which seemed to work fine. I just had to hit the "load" button while in the import section of the web gui (but I am assuming you have done this already).
I have struggled understanding why you cannot simply just point to an oVirt VM file and import this way, or "import" an export domain that already exists.