Oooh, this is getting more posts.
To the post above, in this thread, every single detail was counted, so the fonts changing in Race Game counted as a redesign, and Bonus Game got New electronic screens recently instead of blue backlights. In hinesight, I think the answer is Do the Math, but if you count a single pencil not standing up anymore as a major set design, then Vend-O-Price (Yes, I said earlier that a knob broke, but that isn't a set redesign... unless they reinforced the knobs).
I actually don't believe that we firmly answered the second part, involving the longest time since the redesign. I am willing to think it is Make your Move, by I honestly haven't looked it up yet, or thought about this topic for a while. Blind guessing, I would say Shell Game, because you can only change the table so many times, and I think it has been the same table for at least 7 seasons (Someone fact check me).