[Koha] Re-catalogue a library

I would appreciate any tips, hints or suggestions for re-cataloguing a 7000 item library. At the moment, an item is scanned and then the record updated via Z39.50 but this is a slow process. What other approaches are there? Thank you, Clint. -- Clint Deckard 136 Tukituki Road Ashley Clinton RD1 Takapau Central Hawkes Bay, New Zealand.