I would like to retire a old host. How could I transfer all the Cloudera Manager managed data(hdfs data, impala data, etc...) into a specific new host.
You have to make a difference between the actual HDFS data (blocks) and the Hadoop services on the host.
Simply said, HDFS takes care of replicating the data to other host if you are removing one (called de-comissioning in Cloudera Manager).
However, services will need to be manually assigned to the new host. Also, there could be some difference whether you are dealing with worker (like datanode, nodemanager) or master (namenode, resource manager) roles.
If you desribe what services do you have on your host you wan't to retire, I can be more specific.