How can previous money, acquired from work involving ambiguities, be purified if none of it remains, and is it sufficient to establish a charitable project through one's own effort instead of money for repentance and the purification of those funds?

If a married couple repents from earning unlawful money, then they are not accountable for what they have already spent from it. If any of it remains, they must dispose of it by spending it on charitable causes, unless they are in need of it, in which case they may take what suffices their needs and dispose of the rest. The sister who asked the question is not obligated to establish a charitable project to expiate for her unlawful earnings, but if she volunteers to do so, she will be rewarded, and it will expiate her sins.