I’m thankful for your wish to do what’s right; it’s a clear sign that God has been at work in your life. And yes, you should do whatever you can to undo what you did, even though it was long ago and you aren’t able to repay those you hurt.
The Bible urges us to make restitution when we’ve harmed someone or taken something that isn’t ours. When a tax collector named Zacchaeus (who probably had grown wealthy by defrauding people) committed his life to Jesus, he declared, “If I have cheated anybody out of anything, I will pay back four times the amount” (Luke 19:8). Making restitution is not only important after stealing from an individual; occasionally I’ll hear from someone who cheated on their income taxes and now wants to make things right.
Although you can’t repay the person you cheated, the money you stole still isn’t yours to keep. Ask God to guide you to a ministry or charity in your area (such as a homeless shelter) that could put the money to good use. Don’t just repay the original amount, but take into account what it would be worth in today’s dollars (with interest).
Above all, make it your goal to live for Christ every day, and to follow Him in every area of your life. Thank Him for forgiving all your sins, and thank Him, too, for the hope you have of heaven — not because of your goodness, but because of Jesus Christ and what He did for you through His death and resurrection.