According to Maimonides, and the methodology of Rabbi Eliyahu Dessler z'l, when a person elevates himself to a higher level and thereby makes it easier for himself to observe certain mitzvos that he has mastered, he is no longer judged for performance of those mitzvos, since they have become easy for him. This is compared to a ladder. A person doesn't worry about what portion of the ladder he climbed previously, or what will happen as he climbs higher. Rather his service is to conquer the evil inclination at whatever level he is at.
Rav Hutner z'l, however, based on Rabbeinu Yona, takes the approach that a person who enjoys a higher level is rewarded constantly after he overcomes the previous level as if he was still fighting and winning the earlier battles against the evil inclination.
Take for example, a person who asks G-d in his prayers in the morning, "Let me not come to any tests (in performance of mitzvos) today." In this scenario we'll take it a step further; let's say that there had been a test awaiting him that day from heaven. But because of this fervent prayer not to be tested, his prayers intervened in heaven and he was not tested
Such a person, according to Rav Hutner z'l, would get to the World to Come and find on his list of merits that on that day, he was tested and he passed the test. The person would say, "I don't even remember that happening!" That would be because it didn't happen, his prayers took him to a level where he wasn't tested, but he was merited as if he had been tested and had passed.
[This is especially inspiring to tell people who are interested in becoming religious. Not only will they be rewarded for their new mitzvos, but if they are currently involved in bad things, they will be rewarded every day for turning away from evil, even long after the desire to do evil stops tugging away at them. - webmaster's note]

- based on R. Kaganoff's speech, 9/25/99