Is it obligatory for me to perform Hajj on behalf of my father, who performed Hajj on foot 40 years ago and performed Umrah twice, and is illiterate?

Hajj is obligatory only once in a lifetime. And whoever performs Hajj on behalf of his father, it is considered a supererogatory Hajj, and there is a great reward in that for the one who performs Hajj and for the one on whose behalf Hajj is performed.