If you already have a configured monitor and want to use it in another project of yours, you can clone the entire server to a project you want:
Switch to the Monitoring page of the project with the configured monitor.
Right-click the server holding needed monitors and select Clone Server, or select the server and click on the toolbar.
In the Clone Server dialog, select load tests or projects to which the server should be cloned and click OK. See the sample image below:
ReadyAPI will clone the monitor to all selected load tests.