You can repeat one subject - any subject. Many students repeat Maths if it is an entry requirement for their chosen course. Your points won't change unless you repeat 6 subjects and improve on your existing points. To repeat Maths, you just need to register as an external candidate in a Leaving Cert exam centre by end of January. Look up State Examinations Commission for External Candidate details. If you don't attend school, to repeat one subject was €109 in 2009 but there are no fees if you have a medical card. If you just sat your LC you should review your exam paper in your school on 28th/29th August to make sure marks were awarded and added up correctly and to get a re-check done if necessary. I think private grinds one to one are the best way to repeat one subject such as Maths as you can get a job/sign on/do a PLC course at the same time.