Generate PDF from Reporting Services - cache problem

I develop reports with Reporting Services server and WCF as data sources
Reports are generated in PDF format.

I could not see changes in my reports after updating data.
I found the solution on Peter's Gekko blog.

I added  following  to my report url:

&rs:ClearSession=true

Here is my code:

var reportUrl = ConfigurationManager.AppSettings["ReportURL"];


var reportParameters = @"&rs:Command=Render&rc:toolbar=false&rs:Format=PDf&rc:OmitFormulas=true&rs:ClearSession=true&id=";


System.Windows.Browser.HtmlPage.Window.Navigate(new Uri(string.Concat(reportUrl, reportParameters, myId)), "_blank");