frequency of the client visiting the shop / restaurant
how often the client visit the shop / restaurant
frequency(頻度)もoftenも頻度表す表現です。「お客がどの頻度でお店を来店しているか」は上記に挙げた’frequency of the client visiting the shop / restaurant’もしくは’how often the client visit the shop / restaurant’で表し、「お客様の単価もだけど来店頻度を上げることも売り上げにつながる」は 'The expenditure of each clients is necessary to say, however the frequency of the client visiting the shop / restaurant will contribute the profit of the shop/ restaurant.' などと表現できます。参考になれば幸いです。