How can I reload oozie job configuration file without restart oozie job

the latest oozie 4.1 allows to update coordinator definition. See https://oozie.apache.org/docs/4.1.0/DG_CommandLineTool.html#Updating_coordinator_definition_and_properties

The properties of oozie coordinator can be updated using below command once the coordinators start running. Update the property file in unix file system and then submit as below.

oozie job -oozie http://namenodeinfo/oozie -config job.properties -update coordinator_job_id

Note that all the created coordinator versions (including the ones in WAITING status) will still use old configuration. New configurations will be applied to new versions of coordinators when they materialize.

Not really (well you could go into the database table and make the change but that might require a shutdown of OOZIE if your using an embedded Derby DB, and besides probably isn't advisable).

If you need to change the configuration often then consider pushing the value down into the launched workflow.xml file - you can change this file's contents between coordinator instantiations.

You could also (if this is a one time change) kill the running coordinator, make the change and start the coordinator up again amending the start time such that previous instances won't be scheduled to run again.