Livechart updating problem (winform and C#)

void getMonthDetails()
        {
            var months = new[] { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };

            DateTime dt = DateTime.Now;

            int mm = dt.Date.Month;
            int yy = dt.Date.Year;

            string monthsArranged = "";
            for (int i = mm; i <= 11; i++)
            {
                monthsArranged += ("\"" + months[i] + "/" + (yy - 1) + "\", ");
            }

            for (int i = 0; i <= mm - 1; i++)
            {
                monthsArranged += ("\"" + months[i] + "/" + (yy) + "\", ");
            }


            cartesianChart1.Series = new SeriesCollection
            {
                new LineSeries
                {
                    Title = "Book Issued",
                    Values = new ChartValues<double> {504, 813, 895, 402, 687, 895, 467, 1087, 975, 542, 687, 465 }
                },
                new LineSeries
                {
                    Title = "Book Returned",
                    Values = new ChartValues<double> {306, 407, 703, 704, 796, 1023, 745, 685, 535, 1044, 596, 654},
                }
            };

            cartesianChart1.AxisX.Add(new Axis
            {
                Title = "Month",
                Labels = new[] { monthsArranged.TrimEnd(',', ' ') },
                LabelsRotation = 90
            });

            cartesianChart1.AxisY.Add(new Axis
            {
                Title = "Books",
            });

            cartesianChart1.LegendLocation = LegendLocation.Bottom;

        }


      private void UserControl1_Load(object sender, EventArgs e)
      {
            getMonthDetails();
      }