Those that are involved in kiruv give their hearts and souls to help other Jews become closer to Hashem. They exert every effort to help them do teshuva and become more observant. A very important tool in helping other Jews is prayer. To pray to Hashem that they become closer to Him.

This is evident from a story related in the Gemara (Brachos 10a). The Gemara says, “There were these hooligans in Rabbi Meir’s neighborhood who caused him a great deal of anguish. Rabbi Meir prayed for God to have mercy on them, that they should die. Rabbi Meir’s wife, Berurya, said to him: What is your thinking? On what basis do you pray for the death of these hooligans? Do you base yourself on the verse, as it is written: “Let sins cease from the land” (Psalms 104:35), which you interpret to mean that the world would be better if the wicked were destroyed? But is it written, let sinners cease?” It is written ‘Let sins cease’. Rather, one should pray for an end to their transgressions, not for the demise of the transgressors themselves.” It seems clear from the Gemara that one may pray that someone else should repent. Which is also indicated by the Zohar (Medrash Neelam Vayeira). Yet, after analyzing the commentaries this may not be as clear as we shall discuss in this chapter.

The Question of the Maharsha
The Maharsha on this very Gemara, raises a fundamental question: How can anyone pray that someone else should repent? Does this not violate the principle of free choice that “all is in the hands of Heaven except for fear of Heaven” (Brachos 33b), meaning that Hashem does not predetermine or otherwise interfere with a person’s free choice? The Maharsha explains that it is one thing to pray for Hashem to help one’s own effort to repent, as we do in shemoneh esrei, since that is using your free choice to ask for assistance. Therefore, any spiritual improvements that results can be attributed to the person’s own free will rather than to an act of God. But when it comes to praying for someone else, this explanation does not suffice. The Maharsha does not answer the question. It would seem that he would practically not advise praying for others to do teshuva.
The Chazon Ish (O.C. Hashmatos 156) maintains that there is no difference between praying for one’s own spiritual improvement and that of another Jew. Just as praying for help in one’s own moral struggles is appropriate because the person himself is making the free-willed choice to do whatever possible to come closer to Hashem, so too, is praying on behalf of someone else. Since all Jews are responsible for one another and are thus like one person. When one prays for another Jew it is he who initiated this process and is therefore not an interference in our free will, but rather a result of our free will.
Rav Efraim Greenblatt zt”l, the author of Rivevos Efraim and a student of Rav Moshe Feinstein zt”l, offered a similar view to that of the Chazon Ish and Rav Moshe (Igros Moshe O.C. 4:40:13) rejected it and maintains that it is not satisfying. Rav Moshe agrees with the Maharsha that one may not pray for one to do teshuva. How then could Rav Meir pray for the sinners to stop sinning? Rav Moshe explains that often times one sins due to their circumstances. For example, there are people that would like to keep Shabbos but find it difficult to do so because they are in need of money and there is a temptation of parnassah etc. One may pray, argues Rav Moshe, for Hashem to send them wealth in a permissible way, removing the temptation of money. This was the case with Rav Meir. According to Rav Moshe one may not pray for someone to become closer to Hashem, however, you can pray for their physical circumstances to change in the hope that this will lead them to choose on their own to come closer to Hashem.

Summary and Conclusion
A very important tool in helping other Jews become more observant is prayer. To pray to Hashem that they become closer to Him. This is evidenced from the story og the Gemara where Rav Meir prayed for sinners in his community to repent. However, the Maharsha feels that this is improper as this violates the rules of free choice. Namely that Hashem will not interfere in another’s life in order to cause them to become more observant. Rav Moshe Feinstein zt”l agrees with the view of the Maharsha. According to Rav Moshe one may not pray for someone to become closer to Hashem, however, you can pray for their physical circumstances to change in the hope that this will lead them to choose on their own to come closer to Hashem. The Chazon Ish disagrees with the Maharsha and he feels that one is permitted and even recommended to pray for others to become more observant.