Totally trusting the esteemed Jean-Claude Tremblay, after his comment, and my post regarding it, I wanted to try it. So using the link bit.ly/wjCva, I downloaded the prepress profile and installed it. Then I made a PDF from an image and cropped it in Acrobat.

Upon reopening the Document> Crop Pages dialog you can see that the cropped elements are still there and could be uncropped:



Then I selected "Set Media Box to Crop box and Remove objects outside Cropbox" and clicked Analyze and Fix:



A second or two later the Preflight profiles dialog indicated that it had been done:



Next I went back to the Crop dialog (Document> Crop pages) to see that the cropped part of the image was totally gone and it is:



And as Jean-Claude notes, a special thanks Leonard Rosenthal of Adobe for his expertise.