One of the reasons that the first Treaty referendum was rejected was that there was a chance that we would lose our Commissioner. There were other reasons too but that seemed to be the one most talked about at the time. You need to understand the reasons for referenda in Ireland. Our constitution cannot be altered without a referendum, and the same question can not be put to the people twice. The EU asked what needed to be done to pass it in Ireland and the Commissioner bit was removed and a few more tweaks made and it passed the second time. A referendum result is legally binding in Ireland unlike the UK which does not have a written constitution.
To those saying that they have voted once and voting again is undemocratic, I ask was Theresa May's snap election also undemocratic? The government was only about 2 years old when she called the election. Was that against the will of the people? (besides being spectacularly foolish)
Here's some interesting reading on the second Lisbon referendum which bears some striking similarities to the predicament that the UK finds itself in currently. Lies were told and apathy set in. Once the electorate had time to educate themselves and debate the issues informed decisions were made.