There are no right or wrong answers here, and of course, the ones you choose to use in your essay will depend upon the focus of the particular question and the angle from which you approach it. Some phrases that relate to “academic success” are academic achievement,excellence, scholarship, academic arena, intellectual development, effective learning strategies, motivation, diligence.
Though thinking carefully during the planning step can help you minimize repetition in your essay, repetition is still something you should watch for when you’re proofreading. Making a slight change in a word or phrasing is quick to do and can introduce greater variety and effectiveness in your choice of vocabulary.