What should I do about the words of some girls who remind me of my bad deeds before I became committed, and accuse me of hypocrisy when I enjoin good, despite my repentance and remorse?

A person must enjoin good and forbid evil, for this is the function of the prophets. Allah has made the Muslim nation the best nation because of its performance of this duty. Therefore, the questioner must continue advising and inviting (to Islam), and endure harm, as what she is doing is a form of jihad.

As for some people reminding her of the past, this is ignorance; for one who repents from a sin is like one who has no sin. If Allah accepts the repentance of a polytheist, then what about one who repents from a lesser sin? Moreover, no one is infallible from sins except whom Allah protects. If those who have a past were to refrain from inviting (to Islam), then no one would invite. What matters is the perfection of the end, not the imperfection of the beginning. It appears that they say this for the sake of argument.

Her past may even be a reason for her words to be accepted and for her argument to be strong, because she is enjoining them to truth with knowledge, conviction, and experience. So, she should continue advising them and seeking reward from Allah.