Hi Mayaruru,
Ireland is a lovely place to spend time- I hope you find a way to get there that is right for you!
Unfortunately, I am not very familiar with year abroad programs for teens. But there are a number of ways to get to Ireland if you don't mind waiting a while. You could go as an au pair, which means you'd be staying with an Irish family, helping in the house and minding the children. Usually au pairs also get an English language course as a part of the deal. If you plan to go to uni, you could do an ERASMUS semester at an Irish university. There are also a number of companies in Ireland (especially in Dublin) who hire people to do German-speaking work- for this option you'd of course have to wait some time, though!
If you're looking to go there in the nearer future, perhaps doing a summer course for teens at a language school could be suitable for you. It's not a full year, but it would give you a chance to first get a taste of what it's like in Ireland. I previously taught at a school called Atlas Language School in Dublin. They've got a summer program for teens, and I know them to be a good language school with really lovely teachers. Maybe look them up on Google and see if they offer something of interest to you.
And in the meanwhile, you can have a look at this docu-series by Des Bishop. It's about himself trying to learn Irish: Part 1:
http://youtu.be/uPqoKpyhzP8
I hope that helps you!