Geeee >_< my condolences. Talk about ... well, would that be 
considered false advertising? (More like "non-advertising" - 
like the repro Nausicaa cels in a different thread.) 

Exactly where were the lines redrawn - and how? A normal 
ink pen on the front of the cel, I assume? You might consider 
adding a layer of acetate on the front and finish the lines 
on that, or even directly on the cel itself (but that doesn't 
sound very good). Line corrections isn't an uncommon thing 
in Japanese studios, but they take a xerographic copy on 
another cel layer and put it on front.. 

You might even consider getting it professionally restored, 
but I don't know how that would work, it's probably expensive,
and it depends on how much more you're willing to put into 
the cel. I'm inclined to say redo the lines yourself, but 
how you do it is another issue...

(Warning to all who do eBay! Ask about numbers, closeup scans, 
condition, whatever!)