While I know Data can't be easily rebuilt because of dramatic weight reasons, I find it very hard to see how in the 23rd century Pike and his friends can easily replicate an extremely advanced exoskeletal spacesuit, yet they can't even replicate Data in the 24th. Dr. Soong surely would have left blueprints on how to replicate his physical components and how to back up his mental components.I’m pretty sure Data is long gone and never rebuilt. The one we see is really part of a holodeck recreation that Picard runs because he misses him so much. That’s why he says that he wishes the game wouldn’t end, because when it does Data goes back to being dead and Picard isn’t able to pretend for a brief moment that he’s still there.