What are the conditions for repentance and expiation for sins for a remorseful girl who did not pray or fast out of laziness, committed fornication twice, frequently swore falsely and slandered women's honor, and was disobedient to her parents?

What you have mentioned about abandoning prayer and fasting, committing immoral acts, disobeying parents, and other major sins indicates a severe weakness in faith. Therefore, one must hasten to sincere repentance before it is too late. The door of repentance is open to every person before the sun rises from the west or before witnessing death, as Allah Almighty says: "Say, 'O My servants who have transgressed against themselves [by sinning], do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, it is He who is the Forgiving, the Merciful.'" [Az-Zumar: 53]. And you must perform many good deeds and acts of obedience to expiate sins, because "Indeed, good deeds do away with evil deeds." [Hud: 114].