Hello @Edward_Gonzalez,
Reauthorizing a core is as simple as logging in again. Upon logging in Roon will provide a popup window asking you if you want to de-authorize the previous core and authorize the current one, this process should be relatively quick and should only take a couple of minutes at most.
There should also be the option of choosing to run the Antipodes EX as a Roon Remote and keep your Core as the CX. If using this configuration, you will keep the EX only as a renderer (Roon Remote) while the CX remains the Core. Hope this explanation helps but do let me know if you have any other questions.
Thanks,
Noris