Update parent form from child form

I currently have a parent form that you search for a project. It then
displays the project information and gives a few options with a couple
buttons. Now when you click on of the buttons, it brings up a popup
where you can import an excel spreadsheet which then upon a successful
import, I would like to refresh the parent page as the imported file
will have updated information regarding the project. But because the
parent page has a search, when I refresh the page using

const string cRefreshParent = "<script language='javascript'>" + "
window.opener.document.forms(0).submit();" + "</script>";
const string cRefreshParentKey = "RefreshParentKey";
this.Page.ClientScript.RegisterClientScriptBlock(this.GetType(),
cRefreshParentKey, cRefreshParent);

it refreshes the page and doesn't have any information displayed. I
then have to type the project number in again and click search and it
will then display the new information.

Is there a way to 'click the button' from the child form? The button
doesn't have a click event but rather is opened using javascript with
the following code:

impBtn.Attributes.Add("onclick", "window.open('insertPage.aspx?
PROJNUM=" + pn+ "',
'newwindow','width=450,height=250,menubar=yes,toolbar=no,resizable=no,
status=1');return false;");