There’s nothing in the contract that states the license must be be renewed just because they’re adding more or improving Potter attractions -BUT- as business practice, it would be unwise of WB to cancel any of their contracts while Universal is showing they’re willing to continue to make investment in the property THEREFORE it’s in Universal’s best interest to continue to invest to ensure they’re looked upon favorably every time a renewal period is up, which for the older lands like Hogsmeade is every few years now.
Nothing contractual about it, but helps ensure security.
Also worth noting that each land after Diagon is technically governed by its own licensing agreement, so WB could theoretically cancel a contract for one area when renewal is up if they choose to do so, while keeping the other areas’ contracts in place.