Answer: Why would a person have ascents and descents once he completes his correction? The purpose of descents is to reveal another uncorrected desire to you—to make you dig more deeply into your egoism, to discover there something that needs to be brought to the surface.
It’s similar to the way the ground is plowed before planting seeds. These are all consequences of our spiritual work.
Once a person reveals his entire uncorrected desire and corrects it, there is no reason for descents or ascents. But he will continue to ascend and descend until he reaches the end of correction, Gmar Tikkun.
From the 1st part of the Daily Kabbalah Lesson 11/3/2011, Writings of Rabash