Keritot 27 - One Cannot Re-Use A Sin-Offering
If one designated an animal as his sin-offering and then died, his son cannot bring it, even if his son committed exactly the same sin. One may not even bring his sin-offering, which designated to atone for one transgression, for his other, and even if it is exactly the same. Thus, if one designated a sin-offering for forbidden fat he ate last evening, he cannot bring it to another for the forbidden fat he ate today. Why is all this? Because the Torah said, "he shall bring his offering for his transgression," and two extra words "his" exclude any re-use of a sin-offering.
If a wealthy individual designated money for the purchase of a female lamb as his sin-offering, and then became moderately poor, he can use this money to bring a bird instead. If he became even poorer, he could use the money to bring his flour offering.
The other way around is also true: if we was very poor and designated money for his flour offering, but then prospered to the point of being only moderately poor, he can add funds and bring a bird. If he became wealthy, he can use the money (and add some more) and bring a female lamb.
Art: Jean Bourdichon - The Wealthy Man