Web Forms :: How To Add Multiple Textboxes At Runtime And Maintain Them After Postback

I'm trying to make a form that could have one or multiple textboxes. I have a textbox and a button to add additional textboxes.

I have no problem adding a second textbox inside a panel but I want to be able to keep adding more textboxes every time the link button is clicked and later reference those boxes to be saved. I would also like to maintain the value of the textboxes there. They are not saved to the database until all the necesary texboxes have been added.

I added the textbox using:

private void button1_Click(Object sender, System.EventArgs e)
{
TextBox textbox1 = new TextBox();
panel.controls.add(textbox1);
}

that works fine, but when i click the button again it doesn't add an additional textbox which is what i need.