Apps can help you out, but don't mix up revising with actually working through the texts. What people forget is that you need to read the whole books, not just summaries or study sheets. When you're working on the written exam, you need to be able to quote accurately, to explain a passage without having it in front of you. The quizzes and multiple-choice tests on apps give you the illusion that you know stuff, but they mostly test your short-term memory. It's like doing 100m sprints every day and thinking you're ready for a marathon.
For the written exam, make yourself problem-focused sheets instead of basic summaries. Like, instead of "the hero faces destiny," write "how does the text deal with the conflict between freedom and determinism, with two or three key quotes." Work on transitions between your ideas too - it sounds obvious but that's what makes the difference. The oral exam is way more about fluidity and your ability to defend an interpretation. You need to reread, to recite out loud, to go up against someone asking you unpredictable questions so you can check if you actually understand it or if you're just repeating stuff.
What exactly is your topic on the syllabus? Because prep depends a lot on whether it's poetry, theatre or a novel.