post back problem

im using  this code
........................................................

 SqlConnection sqcon = new SqlConnection("Data Source=ADMIN-PC;Initial Catalog=raj;Integrated Security=True");



    protected void Page_Load(object sender, EventArgs e)
    {
        if (IsPostBack)
        {
            BindRepeaterData();
           
        }
        Validate();
    }
    protected void Button1_Click(object sender, EventArgs e)
    {



        sqcon.Open();
        SqlCommand cmd =new SqlCommand("insert into repeter_demo(User_Name,Subject,comment,Post_Date)values(@User_Name,@subject,@Comment,@Post_Date )", sqcon);
        cmd.Parameters.AddWithValue("@User_Name", TextBox1.Text);
        cmd.Parameters.AddWithValue("@Subject", TextBox2.Text);
        cmd.Parameters.AddWithValue("@Comment", TextBox3.Text);
        cmd.Parameters.AddWithValue("@Post_Date", DateTime.Now);
        cmd.ExecuteNonQuery();
       sqcon.Close();
        TextBox1.Text = string.Empty;
        TextBox2.Text = string.Empty;
        TextBox3.Text = string.Empty;
        BindRepeaterData();
    }
    //Bind Data to Repeater Control
    protected void BindRepeaterData()
    {
        sqcon.Open();
        SqlCommand cmd = new SqlCommand("select * from repeter_demo  Order By Post_Date", sqcon);
        DataSet ds = new DataSet();
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        da.Fill(ds);
        Rpt.DataSource = ds;
        Rpt.DataBind();
        sqcon.Close();
    }

}

after each post back new row of  repeater show on the page. while controls  are empty .

im using this code at designing  phase

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>





   


   

   

   
   
   
   
    
     
   
   
    
 
     
   
   
    
      
   
  
   
   
   

Enter Name
Enter Subject
Enter Comment

   

   

 
       
       
       
       
       
       
        
       
       
       
       
       
       
       
       
       
       

       
       
       
       
       
       
       
       
       
       
       
       

Comment

Subject:

Post By: Created Date:

       


         
   
   
   
   

   

 

how will i get rid of this problem . 
at out put  i want to clear repeter clear.