@Kaya1, if your referring to setting up URL blocks in the content filtering section of an MX then, if you deployed the environment using templates, then you just need to update the template. But I’m guessing you haven’t use templates, so the next best thing is to use the API to achieve this, you can use this endpoint https://developer.cisco.com/meraki/api-v1/#!update-network-appliance-content-filtering.
if you haven’t used the API and done any scripting it’s worth learning as this is a great way to manage multiple networks.