I would say "yes", an inentional replanning BY CHOICE would be subject to the same restrictions as pre-flight planning. (Anything else would be ridiculous, as you could otherwise routinely "replan" 1 minute after takeoff and legally ignore every rule in the book!)
But that requirement wouldn't be interpreted to apply to abnormal or emergency conditions. Even if it DID, there's a "notwithstanding clause" in JAR-OPS which says, in effect, that you can break any rules you like in an emergency, anyway.