All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
Leaving prayer is a major sin and a great crime and the person who does so is in a serious situation before Allah The Almighty. It suffices to remind that when the dwellers of hell are asked: "What hath brought you to this burning ? They will say: "We were not of those who prayed; "Nor were we of those who fed the indigent; "But we used to talk vanities with vain talkers; "And we used to deny the Day of Judgment, "Until there came to us (the Hour) that is certain." {Al-Muddaththir, 42-47}, Allah The Exalted responds " Then will no intercession of (any) intercessors profit them." {Al-Muddaththir, 48}.
There is a scholarly consensus on this, however, we don`t rule that the person who left prayer is a disbeliever unless he did so out of disbelieving that prayer is obligatory. Accordingly, the heirs of this deceased person should pay someone to perform Hajj on behalf of their father or that one of them performs Hajj on his behalf. This is of course after having performed his own obligatory Hajj. In fact, Hajj should be performed on behalf of every dead Muslim who didn`t perform it and we ask Allah to Accept that. And Allah The Almighty Knows Best.