Hi, sorry for slow response!
Cantonese is not as popular any more and schools were asked to teach Mandarin more. I know there's a Chinese school on Synge Street. I don't have a list of Chinese schools, I'll ask my friends who knows the whereabouts of these schools.
Btw, have you seen http://irishbornchinese.com/articles/20 ... -for-kids/
? I know it's Mandarin, but it's coming to Dublin as well.