I'm assuming you mean JSB ,in which case,....
Re-qualifying for Jobseeker's Benefit You can re-qualify for JB if:
You have used up your full JB entitlement (either 9 or 6 months) and
You have paid 13 PRSI contributions for at least 13 weeks (these contributions can be counted only after you have claimed at least 156 days (6 months) of JB) However if you are working and claiming JB (systematic short-time workers and part-time workers) you cannot simply continue your JB claim when it is exhausted since you must have suffered a substantial loss of employment to re-qualify for JB, (unless you are a casual worker).
If you have lost your job you will have suffered a substantial loss of employment. If you are a part-time or systematic short-time worker DSP will look at your pattern of employment over the last 13 weeks or another representative period to find out whether you have suffered a substantial loss of employment.
For example, if you are getting JB and working 3 days each week as a systematic short-time worker or a part-time worker and your employment pattern has not changed during the course of your JB claim, you will not have suffered a substantial loss of employment and will not re-qualify for Jobseeker’s Benefit when you exhaust your claim. However, if your JB claim ends and your 3 day week working week is then reduced to a 2 day week, you will have suffered a substantial loss of employment and may re-qualify for Jobseeker’s Benefit