Sets or returns whether Microsoft Excel will automatically refresh a PivotTable and the PivotTable cache when Excel opens the document.

 public boolean RefreshOnOpen{ get; set; }
Public Property RefreshOnOpen() As Boolean

          ExcelApplication xla = new ExcelApplication();
          Workbook wb = xla.Open(@"C:\MySpreadsheet.xlsx");
          Worksheet ws = wb.Worksheets[0];
          ws.PivotTables[0].PivotTableSettings.RefreshOnOpen = true;

          Dim xla As New ExcelApplication()
          Dim wb As Workbook = xla.Open("C:\MySpreadsheet.xlsx")
          Dim ws As Worksheet = wb.Worksheets(0)
          ws.PivotTables(0).PivotTableSettings.RefreshOnOpen = true;

RefreshOnOpen is false by default.

When creating or modifying a PivotTable with ExcelWriter, make sure to set this property to see the changes. If this property is not set in code or in a template, the PivotTable will not reflect changes made with ExcelWriter code.

Setting RefreshOnOpen is the same as going to PivotTable Options > Data and checking or unchecking Refresh data when opening the file.