Solrcloud - adding a node as a replica?

[didier deshommes]

Hi,
How do I add a node as a replica to a solrcloud cluster? Here is my
situation: some time ago, I created several collections
with replicationFactor=2. Now I need to add a new replica. I thought just
starting a new node and re-using the same zokeeper instance would make it
automatically a replica, but that isn't the case. Do I need to delete and
re-create my collections with the right replicationFactor (3 in this case)
again? I am using solr 4.3.0.

Thanks,
didier