When you import from SPSS, SAS creates a separate set of SAS format definitions to store any special "label" assignments from the SPSS data. I'm not sure that's what is happening here, but it's probably a good idea to check whether any formats are created and whether they are present when you export back. This article (about a task in SAS Enterprise Guide) provides a little bit of background.
Also, I see that you're using DBMS=SPSS when you import, but SAV on export. SAV should be used in both cases, though SPSS might be just an alias for SAV in this syntax.
... View more