Leviticus 5:6
And he shall bring his trespass offering unto the LORD for his sin which he hath sinned, a female from the flock, a lamb or a kid of the goats, for a sin offering; and the priest shall make an atonement for him concerning his sin. And he shall bring his trespass offering unto the LORD for his sin which he hath sinned, a female from the flock, a lamb or a kid of the goats, for a sin offering; and the priest shall make an atonement for him concerning his sin.
The obligation does not end with the first confession and sacrifice. When a further sin is afterward brought to remembrance, a separate offering is required for that sin. The remembered fault must be acknowledged and atoned for just as the first was. No past offering covers a sin only later recalled.