C# .net refresh whole page contained in splitcontainer

Question

Ok take a look on the pic

My all pages are loaded in the SplitContainer1(Horizontal).Panel2(right one). I want to do a full page refresh contained in the Panel2. As the SplitContainers are contained in the MDIParent, here comes the problem. If i close and reload the page it does not reopen as child in the Panel2 else opens as a standalone window.

this.Dispose();
childform childform1 = new childform();
parentform parentform1 = new parentform();
childform1.MdiParent = parentform1;
parentform1.splitContainer1.Panel2.Controls.Clear();
parentform1.splitContainer1.Panel2.Controls.Add(childform1);
childform1.Show();

This code is used to close childform and then reload the page in the Parentform. But the compiler gives an error on line 5 that it cant access parentform1. i.e.

parentform1.splitContainer1.Panel2.Controls.Clear();

Is there any other nice and easy way to reset whole page to default? Basically i am confused using it in Parent<->Child scenario.