How to refresh windows application?

 
 
Try below things.
1. Paste a Timer control and make it Enabled = "True" and set it's Intervel property. It's in milliseconds
2. Define the logics for download in a method like below
public void DownLoadFiles()
        {
            //Download logic
        }
3. Write below code inside Tick event of Timer. It's calling your method in a separate Thread. The calls will be in an intevel you already set as property of your Timer control
        private void timer1_Tick(object sender, EventArgs e)
        {
            Thread th = new Thread(new ThreadStart(DownLoadFiles));
            th.Start();
        }