...die eigene Anwendung neu starten?

procedure TForm1.Button1Click(Sender: TObject);
var
  FullProgPath: PChar;
begin
  FullProgPath := PChar(Application.ExeName);
  // ShowWindow(Form1.handle,SW_HIDE);
  WinExec(FullProgPath, SW_SHOW); // Or better use the CreateProcess function
  Application.Terminate; // or: Close;
end;