Sys.Application.add_init Not Invoked on UpdatePanel Update

Question

I have a custom UI control which has a JavaScript class written around the AJAX.NET framework. It inherits from the Sys.UI.Control. The control itself is a UserControl. In the render method I wrap the control in a span and give the span's id the ClientID of the user control. This way I can do this later on:

var control = $find('<%= ServerControlID.ClientID %>');

This allows me to get the client object that represents the UI control.

I create the control in Javascript by doing this (also in the render method)

writer.Write(@"<script type='text/javascript'>
Sys.Application.add_init(function() {
debugger;
    $create(General.Filters.AccountGroupFilter,
        " + GetProperties() + @",
        null,
        null,
        $get('" + this.ClientID + @"'));
});
</script>");

This creates the object. It's done inside of the init event of the life cycle.

The problem is that this control is wrapped inside of an UpdatePanel by a consuming page/control. When another control initiates an update all the controls' UIs get redrawn, BUT the init event NEVER FIRES again.

What happens then is when I do this:

var control = $find('<%= ServerControlID.ClientID %>');
if(control != null)
  control.doSomething();

Nothing happens because the $find does not find the control after the AJAX call. I know I'm NOT doing this correctly. Where am I going wrong. The MSDN article for this stuff is pointing me in circles!

EDIT: Figured I'd include the Render method that I'm doing in the UserControl.cs portion

    protected override void Render(HtmlTextWriter writer)
    {
        writer.Write("<span id=\"" + this.ClientID + "\" >");
        writer.Write(@"<script type='text/javascript'>
        Sys.Application.add_init(function() {

        $create(TradePMR.OMS.Resources.UserControls.General.Filters.AccountGroupFilter,
        " + GetProperties() + @",
        null,
        null,
        $get('" + this.ClientID + @"'));
        });
        </script>");

        base.Render(writer);
        writer.WriteEndTag("span");
    }