Student/graduate visa question. Leaving and re-entering the country

Hello. I am an American studying in Dublin. My visa expires at the end of May in which case I will then plan to apply for the graduate scheme. I will not be able to do so until the end of June though. I want to go back the states for the month of June then return to Ireland in July to gather my results and apply for the graduate scheme. My question is, is there a certain amount of time I'm required to stay away before re-entering Ireland? Will I run into any problems with immigration officers?