Hi,
After you've exported your data to an Excel file, open it in Excel. Then go to Tools, Macros, Record Macro. Format your headers the way you want and then click on the Stop Recording button. Save the macro to your Personal.xls file and give it a name that you'll remember. Next month just open the new file in Excel and go to Tools, Macros, and select the macro you created and it will do the formatting for you.
This is assuming that your headers don't change over time.