This topic was raised many times, I always found it's not possible to (or at least to hard to try) to update components allocation for routing operations. Fortunately I had to do it somehow and I manage ...
... copy completely source routing to target but in any case you can also omit some of the areas and create them after save (like material allocation or components assignment ). form create_routing_by_copy_ewb using f_plnty_s ...