Variety can make studying more engaging and effective. Have your student vary their study routine and methods.
Try active learning activities, including exercises like making and memorizing flashcards, summarizing and retyping notes in their own words, teaching concepts to someone else, drawing diagrams, creating mind maps, watching educational videos on relevant topics, and so on.
Don’t rely on solely reading through the same material over and over. As wonderful as reading is, only reading the material can give students a false sense of familiarity. This can create an "illusion of fluency," or the “tendency to be overconfident in our abilities without sufficient evidence.”