Youre probably getting better grades the second time though! Thats what I found! 
Residence is only applicable if its necessary. You wont find case law on that specifically. The only law I found was the Lewi v Lewi case where kid could have stayed home but didnt and he was on the hook for a higher share of costs. For you, if residence is much more expensive than usual then its pretty easy to say no. If kid really wants to do it he will need to find the money.
Im not a lawyer though but you have to ask yourself if its worth at least $5000 in legal fees to fight it. Judges use the Lewi case for kids share of costs....

Residence is only applicable if its necessary. You wont find case law on that specifically. The only law I found was the Lewi v Lewi case where kid could have stayed home but didnt and he was on the hook for a higher share of costs. For you, if residence is much more expensive than usual then its pretty easy to say no. If kid really wants to do it he will need to find the money.
Im not a lawyer though but you have to ask yourself if its worth at least $5000 in legal fees to fight it. Judges use the Lewi case for kids share of costs....