Is it permissible to sell (long-term lease) waqf land that has become dilapidated in order to construct a new waqf with its proceeds, and is zakat obligatory on these proceeds?

If the house is ruined and the land is rented for a sum, this sum is considered revenue for the endowment (waqf) and is owned by the beneficiaries, who may dispose of it as they wish. It is not obligatory to make this sum an endowment, but it is permissible to build a house and make it an endowment. As for zakat, it becomes obligatory on the sum if a lunar year passes while it reaches the nisab (minimum threshold), either when it is distributed to the beneficiaries, or when it is combined with other funds owned by the beneficiary.