public void SetDashboardState(
    DashboardState state
)

Public Sub SetDashboardState(
    state As DashboardState
)

//...
private void DashboardViewer1_CustomizeDashboardTitle(object sender, CustomizeDashboardTitleEventArgs e){
    DashboardToolbarItem resetStateItem = new DashboardToolbarItem("Reset State",
        new Action<DashboardToolbarItemClickEventArgs>((args) =>
        {
            dashboardViewer1.SetDashboardState(CreateDashboardState()); ;
        }));
    resetStateItem.Caption = "Reset Dashboard State";
    e.Items.Add(resetStateItem);
}
public DashboardState CreateDashboardState(){
    DashboardState state = new DashboardState();
    // Set a range for a Range Filter.
    state.Items.Add(new DashboardItemState("rangeFilterDashboardItem1")
    {
        RangeFilterState = new RangeFilterState(new RangeFilterSelection(new DateTime(2015, 1, 1), new DateTime(2017, 1, 1)))
    });
    // Specify master filter and drill-down values.
    state.Items.Add(new DashboardItemState("gridDashboardItem1")
    {
        MasterFilterValues = new List<object[]>() { new object[] { "Gravad lax" }, new object[] { "Ikura" } },
        DrillDownValues = new List<object>() { "Seafood" }
    });
    // Set a dashboard item layer.
    state.Items.Add(new DashboardItemState("treemapDashboardItem1")
    {
        SelectedLayerIndex = 1
    });
    // Specify a default tab page.
    state.Items.Add(new DashboardItemState("tabContainerDashboardItem1")
    {
        TabPageName = "dashboardTabPage2"
    });
    // Define a dashboard parameter value.
    state.Parameters.Add(new DashboardParameterState()
    {
        Name = "ParameterCountry",
        Value = "UK",
        Type = typeof(string)
    });
    return state;
}
//...

'...
Private Sub DashboardViewer1_CustomizeDashboardTitle(ByVal sender As Object, ByVal e As CustomizeDashboardTitleEventArgs)
    Dim resetStateItem As New DashboardToolbarItem("Reset State", New Action(Of DashboardToolbarItemClickEventArgs)(Function(args) AnonymousMethod1(args)))
    resetStateItem.Caption = "Reset Dashboard State"
    e.Items.Add(resetStateItem)
End Sub

Private Function AnonymousMethod1(ByVal args As Object) As Boolean
    dashboardViewer1.SetDashboardState(CreateDashboardState())

    Return True
End Function
Public Function CreateDashboardState() As DashboardState
    Dim state As New DashboardState()
    ' Set a range for a Range Filter.
    state.Items.Add(New DashboardItemState("rangeFilterDashboardItem1") With {.RangeFilterState = New RangeFilterState(New RangeFilterSelection(New DateTime(2015, 1, 1), New DateTime(2017, 1, 1)))})
    ' Specify master filter and drill-down values.
    state.Items.Add(New DashboardItemState("gridDashboardItem1") With {.MasterFilterValues = New List(Of Object()) (New Object()() {New Object() { "Gravad lax" }, New Object() { "Ikura" }}), .DrillDownValues = New List(Of Object) (New Object() {"Seafood"})})
    ' Set a dashboard item layer.
    state.Items.Add(New DashboardItemState("treemapDashboardItem1") With {.SelectedLayerIndex = 1})
    ' Specify a default tab page.
    state.Items.Add(New DashboardItemState("tabContainerDashboardItem1") With {.TabPageName = "dashboardTabPage2"})
    ' Define a dashboard parameter value.
    state.Parameters.Add(New DashboardParameterState() With {.Name = "ParameterCountry", .Value = "UK", .Type = GetType(String)})
    Return state
End Function
'...

{
    dashboardViewer1.SetDashboardState(CreateDashboardState()); ;
}));

Dim resetStateItem As DashboardToolbarItem = New DashboardToolbarItem("Reset State", New Action(Of DashboardToolbarItemClickEventArgs)(Sub(args)
                                                                                                                                           dashboardViewer1.SetDashboardState(CreateDashboardState())
                                                                                                                                       End Sub))