After a person makes sincere tauba, he needs to start making amends by performing his Qadha Salaah, keeping the missed fasts, paying the outstanding Zakaat etc. If the person passes away in this process of making amends with out completing these obligations, then there is hope that Allah will forgive him and wipe it off. If a person owes someone money, he needs to pay it back. He cannot say that he has made tauba so he doesn’t need to pay back. If a person has done this then he is insincere and his tauba is incomplete.