There isn't any way to repair the hob.
If it's a big scratch, it could potentially be dangerous (ie risk of an electric shock). Have a look at your manual and see what it says there too.
Nicola
I think there is no risk of electric shock as all the electrics are under the glass.It s hard to see how the scratch will make any real difference unless its very deep except it won't look good Make sure the hob is included in your insurance policy for accidential damage just in case the scratch is so deep that it causes the glass to break in the future
The risk of electric shock is mentioned in the manuals of several ceramic hobs on the internet...So presumably there is a risk of this, even if it may be a low one(in the case of a large deep scratch)
There is no risk of shock unless the glass cracks right through. As others have said, it is not possible to repair the scratch so unfortunately you'll have to live with it or replace the hob. It is possible to replace the , but it would be as cheap to replace the entire unit.
Leo
As above - not much you can do about scratches but surface scratches are usually harmless. Only very deep scratches that might cause the hob to crack/break further are a concern. In this case your accidental damage house insurance may cover it.
if its a small scratch and you are only noticing it because its new then I wouldn't worry about it. There'll probably be plenty more to come! You'll stop caring about those small things after a while. Out of interest, how did he/she scratch it?