Is another expiation obligatory for one who broke his oath and committed the sin after giving the expiation, then repeated the act several times? And is it permissible to give the expiation in money?

If you swore not to commit a specific sin, and then committed it, an expiation for breaking an oath (kaffarat yamin) becomes binding upon you. If you rendered it, and then returned to the sin, another expiation is not required of you; because the oath is dissolved by the first breach, unless you intended, by repeating the sin, to repeat the expiation, or if the wording of the oath implied repetition.

As for rendering the expiation for an oath in cash, it is not permissible according to the majority of scholars; rather, it must be in the form of food. However, some scholars permitted rendering its value if it proves more beneficial for the poor. It is advised to avoid sins and to engage in sincere repentance.