This issue has been brought up many times but never solved fully.

I have Load Action code to dynamically assign a prefilter value to a lookup control:

lupProduct.LookupPreFilters.Clear();
oFilter.LookupEntityName = "Sage.Entity.Interfaces.IProduct";
oFilter.PropertyName = "Family";
oFilter.OperatorCode = "=";
oFilter.PropertyType = "System.String";
oFilter.FilterValue = o.Type;
lupProduct.LookupPreFilters.Add(oFilter);

This works fine for the first record loaded, but when I switch to another record with a different o.Type, the filter still just remembers the first record's o.Type. And will only update after you log out/log back in, or re-deploy/resetiis.

Any ideas on how to get this to update after each record change?

This is fixed in 7.5.4 with an Invalidate cache and 7.5.3 WR6 I believe. But I have documented here as well. http://codesnap.wordpress.com/2011/05/16/dropdownlistsaleslogix-lookup-issue/

I tried the method described in your post but still not resolved...

Here is my code:

<p>System.Web.UI.WebControls.DropDownList list;
Type type = lueProduct.GetType();
list = type.GetField("_List", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance).GetValue(lueProduct) as System.Web.UI.WebControls.DropDownList;
 

if (list != null)
{
 list.Items.Clear();

 lueProduct.LookupPreFilters.Clear();
 oFilter.LookupEntityName = "Sage.Entity.Interfaces.IProduct";
 oFilter.PropertyName = "Family";
 oFilter.OperatorCode = "=";
 oFilter.PropertyType = "System.String";
 oFilter.FilterValue = o.Type;
 lueProduct.LookupPreFilters.Add(oFilter);

}