Hi,
"HFSS - Scripting" can be used to export S-Parameters automatically. First manually record the steps involved in exporting s-parameter to 'vb script file'. This can be done by selecting the menu item "Tools>Record Script to file". Created script file can be edited to export many set of solution data.
Or
In HFSS scripting Help, Example file to export S11 data is provided. This can be modified to accomplish the task. I am attaching same script for your convenience.
Hope this helps...