I would think that it would be better practice to specify a note that says that you want the dims to apply after plating.
What is the actual dim you want a hole (for example) to be after plating? I think that it would be alright to put a note on the drawing that states dim's apply after plating. (if that is what your final dim needs to be). I think in either case you would put a note on the drawing that would state thickness of the plating. So why change the model unless you really need to for some other reason.
Its the classic dilemma between design specifications and QC specifications. We're currently trying to find a way to convey all these types of information and, unfortunately, its tending to result in two different models, two different prints, etc.
If you actually manufacture a part from your Pro/E part, you can't model it with dimensions that include secondary operations like plating.
If you only need a drawing of the finished part with the plating I would just bite the bullet and adjust every dimension by the plating thickness. You will have to increase the tolerances too. If you need two drawings, one unplated and one plated then your best bet is to take dougr's first suggestion and add a plating feature. Then you can put the plating feature in a family table.