As far as I know, only the AOB is updated automatically, but I think it's correct only if you're not moving, and the target is moving straight ahead. You've got to update the range manually.
However, skookum mentions an excellent intercept method during which you can safely ignore target range in this thread:
http://www.subsim.com/radioroom/showthread.php?t=151842
To make it short, IF the AOB and speed you enter is correct, and the gyroangle is 000, and the target's path is perpendicular to yours, then range does NOT matter.