Okay, it doesn't change the outcome, but I do want to explain what is actually happening. It's not really de-initialize and re-initialize. It's two separate things.
1. Smart motor initialize - This is done to set the normal operating current and stall current of the motor. When you run the window up and hold the button, it stores a new value for normal motor current. This is used for the "anti-pinch" feature. It's a safety to stop and slightly reverse the window if your arm or something gets caught in it. There is no need to remove power or anything else for the re-initialize procedure to work.
2. Motor indexing ("de-initialize") - The smart motor keeps track of approximately where it is. If it thinks it is lower than it really is, when the window goes full close it will think that it has hit someone's arm and reverse back some. I'm sure that the procedure that Jeff linked to works. Alternately, you can move the old regulator to the same starting position as the new one before moving the motor over. Usually that isn't practical since the old regulator is often not functional. What I usually do is temporarily attach the motor to the new regulator and move it all the way up. Then remove the motor and hit the up button. When the motor times out and stops, attach it to the regulator and move it as needed to install it.