You may just have to encourage them to the new site. Even though they can see the coop they will still be thinking.....Hey What Happened Here! That homing beacon leads them back to the same spot. They may even give you the stink eye for a bit. Hopefully the new run door is easy for them to spot. While your moving you coop I bet they will have a lot of interest. They will adjust. But maybe not without some squawking.
Thanks Chick Charm. That's pretty much what I thought, but I have no experience of this. What if we move it gradually by a a foot a day or something (tedious)? Or what if we move the coop at night when they're in it?!