Extending Tapered loft

I have designed an Aerofoil tapered wing section to make a mould for a friend. I lofted the lower foil section to the upper (smaller) foil section to create the solid tapered wing.
It turns out that the template he gave me was incorrect and the height needs extending following the the same taper I already have. I have thought of ways of doing this by putting isocurves on my solid and extending them, but is there an easier way of doing this. I am using Rhino 4
Many thanks

Hello - impossible to picture what you are up to without the geometry in a Rhino file - please post something here or to tech@mcneel.com with a link back to this topic in your comments.