If you haven't been before, it's worth a look. The archives display is usually pretty good, and gives you a chance to see what it was.
I think they need to do a few things:
Food Building: get some better/interesting vendors in there. It's bit too much like a mall food court.
Grounds: somehow make use of the other buildings on the ground. It seems to me like all the beaux arts buildings are cordoned off, which lends the exhibition the feeling that it's in the parking lot of somewhere else.
Exhibitions: why not try and tie in some other shows? I don't know how that would work, but the Sportsmen's show, the Autoshow, etc., would be great to have running at the same time. Why not try and incorporate arts events, surely you could use one of the halls to showcase Toronto based artists.
Parking: Why not look at building undergorund garages and then utilizing the space above for greenery?
Those are just some suggestions, but they boil down to this: the CNE needs to work on becoming relevant and of interest to people's lives beyond the simple fair aspects.