Is money earned lawful or unlawful after fully repaying a loan, knowing that part of the loan was used to pay for travel visa expenses?

If you took out an interest-based loan, you committed a sin that necessitates repentance to God. If you repent, we ask God to forgive you, for "the one who repents from a sin is like one who has no sin." The profits from money borrowed with interest become permissible, because the sin is related to the borrower's liability, not to the money itself, especially if the loan has been repaid.