Distributed association rule mining algorithms are used to discover important knowledge from databases. Privacy concerns can prevent parties from sharing the data. New algorithms are required to solve traditional mining problems without disclosing (original or derived) information of their own data to other parties. Research results have been developed on (i) incrementally maintaining the discovered association rules, and (ii) computing the distributed association rules while preserving privacy. However, no study has been conducted on the problem of the maintenance of the discovered rules with privacy protection when new sites join the old sites. We propose an algorithm SIMDAR for this problem. Some techniques we developed can even further reduce the cost in a normal association rule mining algorithm with privacy protection. Experimental results showed that SIMDAR can significantly reduce the workload at the old sites by up to 80%.