If the old loft is still there, then it is simply a case of pairing the birds up, letting them bring a round of ybs up and then when there driving for the next set of eggs, start to let them out. Cocks first with the hens locked in the box so theres an incentive to stay at the new loft. Keep them really hungry as well. They will go straight back to the old loft, where you should retrieve them straight away and never feed them there. Take them straight back to the new loft and do the same again. If theres any awkward cocks, leave them at the old loft for a day or two with no corn or water and they will return to the new loft pretty sharpish . Its best to do this with hens when there sitting about 5-10 days as their normally pretty kean at this time. It will also help to allow the birds into a temporary aviary while their on their first brood, so they can have a good look around and get plenty of fresh air ;D. Fly them on widowhood and they will fly there bollocks of for you as they will go to and fro from the new to the old loft .