I have found that if the Reload is turned on, it will hit the window page twice for some reason (not desired). If you turn the Reload off though, it will never show the updated page if you are reusing the same window. So far, what seems to work best is to add a random number into the url so the window does not use a cached version (see below). It will only hit the page once, and will also actually display the new page. In my case, without the random number, the url would have been the same, even though the generated page could have changed. If anyone has a better idea, please let me know.
Client function code:
// Need a random item in the querystring so the RadWindow does not pull from cache.
var WinId = "Win" + Math.random().toString();
var Url = "query_preview.aspx?id=" + elReportSavedQueryID.value + "&wid=" + WinId;
var oManager = GetRadWindowManager();
var oWnd = oManager.GetWindowByName("ExportPreviewWindow");
alert("No window object found!");
Window Manager in page:
<radw:radwindowmanager id="RadWindowManager1" runat="server" left="" navigateurl="" skinspath="~/RadControls/Window/Skins" title="" top="">
<radW:RadWindow ID="ExportPreviewWindow" DestroyOnClose="false" Modal="true" EnableViewState="False" VisibleStatusbar="true" Width="600px" Height="400px" NavigateUrl="" />