What is the ruling on giving Zakat to a sick father who has sufficient income, with the aim of increasing his income and seeking his forgiveness, knowing that giving it to ascendants is impermissible? And is it obligatory to give Zakat again?

It is not permissible to abandon or boycott one's father, no matter how much he wrongs you. Rather, it is obligatory to show him kindness and dutifulness. It is not permissible to give him zakat, because zakat has specific recipients, and a father is not among them. His maintenance is obligatory upon his son if he is in need. If he is wealthy, it is not permissible to give him zakat. Therefore, you must re-distribute the zakat to its rightful recipients, the poor and the needy, since you gave it to your father out of ignorance.