If you have been self-employed for the last number of years, it is unlikely that you have the PRSI stamps to be eligible for any benefit payment to lose (although you will of course have access to means tested allowance payments, such as jobseekers allowance, which everyone habitually resident in the State has).
You will only be able to keep any entitlement to Jobseekers Allowance if you are available for and seeking full time work. If you work even one hour in a day (as employed or as self-employed) then you are considered employed on that day. If you are employed more than 3 days in any 6 consecutive days (they don't count sundays), you are not entitled to any Jobseekers payment.
If you are working 30 hours a week or more, then you will also not be eligible for any assistance under the Supplementary Welfare Allowance scheme (eg, rent supplement)