I think the best way is to limit how many times you can repair that item, say one item may be repaired up to 10 times.

1.Any item that has been repair once before will become "untradable", so that player can not sell their second hand item with low repair counts.

2.Any item that has been repair to 10 times then it should get old enough to become "unable to repair" so that it is time for him to buy a new stuff already. (with the current patch, if you are in optimal rank, you can use the gear for full week without repair, so 10 times of repair should make it last long enough for use 1-2 months.)

3.Unique item usually are rare, and they should be allowed to have more repair count to 99x (which is probably enough to use for a few years)

I think asking DoW to buy one set of armor armor every 1-2 months should be good for economy flawlessness. Since most of DoW now has money and have nothing to spend if they not invest it for crafts.