Dynamic textfields does not retain data on postback

Question

I created a webform that allows the user to dynamically add more textboxes. Right now, as the button is clicked to add another field, it postbacks to itself. The controls are added in the Pre_Init. However when the page reconstructs itself the textbox names are different each time so the data is not being retained on each postback.

protected void Page_PreInit(object sender, EventArgs e)
{

    MasterPage master = this.Master; //had to do this so that controls could be added. 
    createNewTextField("initEnumValue",true);
    RecreateControls("enumValue", "newRow");
}
private int FindOccurence(string substr)
{
    string reqstr = Request.Form.ToString();

    return ((reqstr.Length - reqstr.Replace(substr, "").Length) / substr.Length);
}
private void RecreateControls(string ctrlPrefix, string ctrlType)
{
    string[] ctrls = Request.Form.ToString().Split('&');
    int cnt = FindOccurence(ctrlPrefix);
    //Response.Write(cnt.ToString() + "<br>");
    if (cnt > 0)
    {
        for (int k = 1; k <= cnt; k++)
        {
            for (int i = 0; i < ctrls.Length; i++)
            {
                if (ctrls[i].Contains(ctrlPrefix  + k.ToString()) && !ctrls[i].Contains("EVENTTARGET"))
                {
                    string ctrlID = ctrls[i].Split('=')[0];

                    if (ctrlType == "newRow")
                    {

                        createNewTextField(ctrlID,false);
                    }
                    break;
                }
            }
        }
    }
}
protected void addEnum_Click(object sender, ImageClickEventArgs e)
{

    int cnt = FindOccurence("enumValue");
    createNewTextField("enumValue" + Convert.ToString(cnt + 1),false);
   // Response.Write(cnt.ToString() + "<br>");
}
private void createNewTextField(string ID, bool button)
{
    Response.Write(ID + "<br/>"); //this is where I'm getting different names each time there is a postback
    if (ID != "initEnumValue") //create new line starting with the second tb. 
    {
        LiteralControl newLine = new LiteralControl();
        newLine.Text = "<br />";
        this.plhEnum.Controls.Add(newLine);
    }



    TextBox newTb = new TextBox();
    newTb.ID = ID;
    this.plhEnum.Controls.Add(newTb);

    if (button) //create the button only on the first one. 
    {
        LiteralControl space = new LiteralControl();
        space.Text = "&nbsp;";
        this.plhEnum.Controls.Add(space);
        ImageButton imgbutton = new ImageButton();
        imgbutton.ID = "addEnum";
        imgbutton.ImageUrl = "~/images/add.png";
        imgbutton.Click += new ImageClickEventHandler(addEnum_Click);
        imgbutton.CausesValidation = false;

        this.plhEnum.Controls.Add(imgbutton);
    }

    //endEnumRow();
    //this.plhEnum.Controls.Add(newTb);
}

I have tried this solution How can I get data from dynamic generated controls in ASP .NET MVC?