Everytime you enter Thailand it's a fresh new entry in terms of tm30 and the agent/landlord need to lodge a new tm30 by law. If they fail to do it then they can be fined, however, some might argue that for individual landlords/agents this one is bit relaxed or not properly enforced. Although you can always remind that it the law for landlord or agents to lodge tm30 within 24 hours when a foreigner starts residing in their house, otherwise there might be huge fines. It's also clearly written on Royal Thai Police - immigration bureau's website. You can take a screen shot ans share with them. Hope this will convince them to lodge the tm30.