You have to have the figure at x and z 0.  Then before going to the fitting room, adjust the clothing as close as you can to fit, without conforming.  IK off everything, check the figure hip to see it's at x and z 0.  If the hip is off, then it won't conform properly.  The joint editor only resets rotations, it doesn't reset any translations.  My guess would be you have an offset in the x, and possibly in the z for the hip.  Zero them, and it should work properly.  Maybe not the best way to say this, but what I think is happening if the hips and body aren't zeroed, it will adjust to the figure, and when you tell it to make a new figure, the cloth, it won't be at the true zero, but at the zero as set by the offsets.  Like I said, probably the wrong way to put it, but about the simplest I can.

Easiest way to check is to zero out the body in X and Z, then use the little ball to rotate the view.  If the figure moves in a circle instead of pivoting, there are offsets that are going to screw you up.  More than likely the hip.

Doric.

The "I" in Doric is Silent.