Performing Voluntary Hajj on Behalf of Mother

My mother performed the Hajj seven times, so is it permissible for me myself to perform another Hajj on her behalf?

Yes, it is permissible for you to perform another Hajj on her behalf - an eighth Hajj or more - and this is from kindness and honoring towards her, and there is great reward in that for you if you have already performed the obligatory Hajj for yourself.

Sheikh Ibn Baz