What type of license are you using? per-device co-termination?
In co-termination, you just need to remove the old AP from the network and then add the new AP to the network and the license will automatically be linked to it.
In the per-device do an undo assign on the old AP to assign to the new AP.
I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.
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