Assuming that you have enough nodes in the cluster (Elasticsearch will not allocate replicas to any node that already holds a copy), you should be able to use the update indices settings API. 1.3.x is however a very, very old version, so you should really think about upgrading.
Apache, Apache Lucene, Apache Hadoop, Hadoop, HDFS and the yellow elephant
logo are trademarks of the
Apache Software Foundation
in the United States and/or other countries.