If the Irish CAA were complying with Appendix 1 to JAR-FCL 1.005 you would not have to retake the exams.
You next alternative is to obtain a JAA licence on the basis of an Expired ICAO licence in which case you would have to retake the 7 ground exams and take the skill test.
You could obtain a FAA licence where again you would need to take their theoretical exam (probably easier) and pass the Skill test and then convert it to a JAA licence. If you have over 100 hours that would reduce it to 2 exams but you'd still have to do the Skill Test.