Repeat the part you misunderstand, not only the part that makes you feel capable.

Practice drifts toward whatever is pleasant. Running the section you already play well produces a nice sound and the feeling of having worked, while the bar that keeps failing gets one hurried attempt at the end. This is not laziness; competence feels good and confusion does not, so attention slides. The result is a lot of hours spent maintaining what you had and very few spent adding to it.

Start your next session at the hardest part while you are fresh. Give it more time than feels reasonable and stop before you drift to the easy section. Ending on something rough is uncomfortable and much more productive.