Yes I did this last year.
You need need to apply to the court. Get application forms from CRO website, fill them in, get them stamped in the court office, pay the fee, €90 as far as I remember.
The CRO staff were very helpful on the phone, and the court office staff were equally helpful explaining how to get the forms stamped.
It very simple, you need to explain why you were late, but the court will accept that you were busy and forgot basically.
You need to inform the CRO that you are applying and then inform them of the decision.
Its all in leaflet 39 on the CRO website.
http://www.cro.ie/Annual-Return/Missed-Deadlines
It tool 6 weeks from submitting the forms to the court to getting the order.
The only issue is that a solicitor needs to represent you in court when the case comes up. It appears that you cannot represent yourself in this case. In my case I did everything for the solicitor he just confirmed the application in court. I had it all arranged with my regular solicitor, he contacted some other solicitor who was in court that day and acted for him.