I exported my existing datapool and saved it to my local drive as a CSV file. I edited using Excel and added more rows to my data. When I imported it back, the new rows showed up with no problems but the datapool field names defaulted to Field1, Field2, etc... I have about 70+ Columns/Fields and I hate to re-define them again.
I have never used the import export function but I can tell your that the <datapoolname>.spc file in the datapool directory has the column names in it. Perhaps if you back up that file and then restore it the names would be repaired.