Hindus believe in reincarnation and during this life a person should carry out themselves in a proper way- being helpful, kind, caring, honest and most of all uphold their religion and culture (e.g. performing morning sadhana- prayers, keeping clean and worshipping the Lord), in other words- keeping God in the center of their lives. So to reap good karma, one must do all of these things, so in the next life he/she will get a better birth (a poor man in this life will be better off in the next). The first answer is the correct one- reincarnate in a more pure varna- house (life).
