First, go to the database menu, select "Verify Database". If you don't get a message saying that there are differences and asking if you want to "fix up the report", then the report is looking at a view or a command. If you get the message, then the report is looking at the correct table, but it has been given an alias and field should now appear in the Field Explorer.
If you don't get the message, go to the Database Expert and right-click on the table. If "Edit Command" appears as an option, then the report is based on SQL and you'll need to update the command to select the new field. If it doesn't appear in the menu, then the report is probably looking at a view that will need to be updated in the database.
-Dell