The repaint job itself, would be the cheapest. Out of Service and the empty return leg to the sprayer would be the costly one.
I do wonder who is going to pick-up that tab. I do assume, CX did "accept" the airplane in XMN after all the work had been done (otherwise the masking off would have been done in XMN, if the aircraft was urgently needed, probably not), I would not like to be the one who signed off on the acceptance in XMN