silverlight datagrid - WCF Service Data auto refresh

i have silverlight page, it has a datagrid. I have created a WCF service  which generates data for that datagrid. In my silverlight page, i call that service as shown below


                MyService.MyServiceClient mysvcclient1;
                mysvcclient1= new  MyService.MyServiceClient();
                mysvcclient1.GetDataGridDataCompleted += new EventHandler<MyService.GetDataGridDataCompletedEventArgs>(CompletedHereGetDataGrid);
                mysvcclient1.GetDataGridDataAsync();
                mysvcclient1.CloseAsync();
            }

now i want to refresh that data every 30 seconds... what is the best way to do that?


thanks....