Since you mentioned that you are 'refreshing' the data in Excel, it sounds as if you are using Excel's 'MSQuery' feature. Those can be modified and saved; here's how I'd do it in one of my workbooks in Excel 2007. Note that these steps apply to modifying a SQL server-based MSQuery. I've not done a SharePoint-based MSQuery, but hope it's similar:
Click anywhere in the refreshable dataset. Then at the top of your workbook, select 'Data', then 'Properties', then the 'Connection Properties' icon next to the connection name.
That should bring up a "Connection Properties" form, which should have a 'Usage' and 'Definition' tab. Select the 'Definition' tab, then at the lower left, click the 'Edit Query' button.
That should bring up a 'Query Wizard' form. At this point you have 2 nice options:
a. You ought to be able to bring in your new column from here, when you scroll to your source table in that Query Wizard.
b. If you want some more flexibility, you can hit the 'Cancel' button on that 'Query Wizard' form, and it will ask you "Do you want to continue editing this query in Microsoft Query?" Select 'Yes'.
This should bring up a 'Microsoft Query' editor. You should be able to drag-and-drop your new column into the query here. You also have the 'SQL' button at the top, and you can make direct edits to your SQL statement.
Whichever one you choose, when you are done, be sure to then select 'File', and 'Save'.
I hope this works for you; again, I'm not familiar how Sharepoint plays with MSQuery. Best of luck.