If you set calculation to manual in Excel's settings Formulas tab, you can update the functions by pressing F9, or by creating a button that does the update. To create a button, follow these steps:

  1. Open the VBA macro editor (to find the VBA editor in Excel 2007, check Options: Popular: Show Developer tab in the Ribbon. In Excel 2003, you can open the ditor from Tools: Macro: Visual Basic Editor).
  2. In the editor, select Insert: Module .
  3. In the module that opens, paste this code:
        Sub refreshAll()
            Application.Calculate
       End Sub
  4. Close the Visual Basic editor and return to Excel.
  5. In the Developer tab, choose Insert: Button (Form control).
  6. When you have placed the button on the sheet, right-click and choose Assign macro, and as the macro name, type "refreshAll".