I am not sure I understood your scenario completely but several questions come up to my mind.
Do you need to re-bind the RadTreeview when a new item is added or edited? If the TreeView is bound to ObservableCollection<> which implements the ICollectionChanged interface, whenever an item is added to this collection, the RadTreeView gets notified and the Layout of the tree is updated.
You mention that you need to preserve the state of items when reloading/rebinding (with "state" I mean the values of the following properties - IsSelected,IsInEditMode, CheckState, IsExpanded). The best way to achieve this is to use Style Bindings(WPF 4, SL5) or ContainerBindings (for SL4) - property from the ViewModel is bound to a corresponding property from the container - the RadTreeViewItem. You can check out this article for further reference.
All the best,
the Telerik team
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