The correct way is to use the XPression Rundown Controller (free unlicensed software) or XPression Remote Sequencer (paid licensed software) to deactivate and then reactivate the rundown on the XPression MOS Gateway. This will trigger the engines to reload the project. Output engines only load a new project when the MOS rundown is loaded into them.
You could also trigger this action by unloading and reloading the MOS rundown in ENPS to the XPression MOS device. However, depending on the ENPS setup, this may also unload the reload the rundown on all MOS devices, which could be a problem depending on your workflow. The advantage of the XPression Rundown Controller and Remote Sequencer software is that you can trgger that rundown re-load without affecting other MOS devices.