Refreshing all the pivot tables in my excel workbook with a macro

Yes.

ThisWorkbook.RefreshAll

Or, if your Excel version is old enough,

Dim Sheet as WorkSheet, Pivot as PivotTable
For Each Sheet in ThisWorkbook.WorkSheets
    For Each Pivot in Sheet.PivotTables
        Pivot.RefreshTable
        Pivot.Update
    Next
Next

In certain circumstances you might want to differentiate between a PivotTable and its PivotCache. The Cache has it's own refresh method and its own collections. So we could have refreshed all the PivotCaches instead of the PivotTables.

The difference? When you create a new Pivot Table you are asked if you want it based on a previous table. If you say no, this Pivot Table gets its own cache and doubles the size of the source data. If you say yes, you keep your WorkBook small, but you add to a collection of Pivot Tables that share a single cache. The entire collection gets refreshed when you refresh any single Pivot Table in that collection. You can imagine therefore what the difference might be between refreshing every cache in the WorkBook, compared to refreshing every Pivot Table in the WorkBook.

ActiveWorkbook.RefreshAll refreshes everything, not only the pivot tables but also the ODBC queries. I have a couple of VBA queries that refer to Data connections and using this option crashes as the command runs the Data connections without the detail supplied from the VBA

I recommend the option if you only want the pivots refreshed

Sub RefreshPivotTables()     
  Dim pivotTable As PivotTable     
  For Each pivotTable In ActiveSheet.PivotTables         
    pivotTable.RefreshTable     
  Next 
End Sub 

This VBA code will refresh all pivot tables/charts in the workbook.

Sub RefreshAllPivotTables()

Dim PT As PivotTable
Dim WS As Worksheet

    For Each WS In ThisWorkbook.Worksheets

        For Each PT In WS.PivotTables
          PT.RefreshTable
        Next PT

    Next WS

End Sub

Another non-programatic option is:

• Right click on each pivot table
• Select Table options
• Tick the 'Refresh on open' option.
• Click on the OK button

This will refresh the pivot table each time the workbook is opened.