Is it permissible to replace the current lease agreement with a new one to avoid the suspicion of usury, knowing that the landlord refuses to return the advance payment and that the advance payment is in the possession of one of the heirs without the knowledge of the others, and he is the one who will pay them the rent?

If the contract between you and the lessor is a fixed-term (rental) agreement, then it is not permissible for you to pay a portion of the rent in advance in exchange for exemption from paying rent for a specific period, because this is considered a loan that brings benefit, which is usury (riba). Similarly, it is not permissible to replace the contract with a new contract as a trick to fall into usury. The possible solutions are: leaving the contract as it is and recovering the amount through monthly rent, or complete mutual rescission of the contract and recovering the amount, then entering into a new contract if you wish, or resorting to the authorities to recover the amount.