Adding dynamic controls not working

I am creating dynamic pictureBox and label in WinForms. For this I have created a method which creates these items on the basis of given integer. In the first run while loading the form, its works smoothly, but when I pass any integer from a dropdown box, it does not make any changes. I tried debugging the code, and all the labels are created accordingly but it is not reflected in the winForm. I tried using Invalidate, Update, Refresh but non of them worked.

Here is the method that I have implemented.

 private void createPictureBox(int size)
    {
        //this.Controls.Clear();
        panel1.Controls.Clear();
        Label[] ParameterLabel = new Label[size];
        PictureBox[] ParameterBack = new PictureBox[size];
        int y_value = 11;
        this.Refresh();
        for (int i = 0; i < size; ++i)
        {

            ParameterLabel[i] = new Label();
            ParameterLabel[i].Text = "Test Text";
            ParameterLabel[i].Font = new System.Drawing.Font("Calibri", 8, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, ((byte)(128)));
            ParameterLabel[i].ForeColor = System.Drawing.Color.White;
            ParameterLabel[i].BackColor = System.Drawing.Color.FromArgb(1, 0, 64);
            ParameterLabel[i].Size = new System.Drawing.Size(145, 20);
            ParameterLabel[i].Location = new Point(30, y_value);
            ParameterLabel[i].Anchor = AnchorStyles.Left;
            ParameterLabel[i].Visible = true;

            ParameterBack[i] = new PictureBox();
            ParameterBack[i].Image = Image.FromFile(STR_SETTING_PATH + "\\" + STR_IDEA_NO_XXXXX + "_01_nv.png");
            ParameterBack[i].Size = new System.Drawing.Size(400, 32);
            ParameterBack[i].Location = new Point(2, y_value - 10);
            ParameterBack[i].Anchor = AnchorStyles.Left;
            ParameterBack[i].Visible = true;
            //this.Controls.Add(ParameterBack[i]);

            y_value += 37;
        }
        panel1.Controls.AddRange(ParameterLabel);
        panel1.Controls.AddRange(ParameterBack);
        panel1.Invalidate();
    }