Does my sister's intention to pray after her death count, and what are the deeds that will benefit her after her death?

The woman has been excessive towards herself by neglecting prayer throughout her life, and prayer does not fall away from the sick person; thus, she was obliged to pray according to her ability. It is hoped, by the grace and mercy of Allah, that He will overlook her shortcomings and pardon her negligence, especially if she was ignorant of the ruling on prayer during her illness, and her intention to repent and be upright lightens her burden. If she repents with sincere repentance, it is hoped that Allah will accept her repentance and forgive her. And you are obliged to supplicate and seek forgiveness for her, and to give charity on her behalf.