Many authors insist you should repot your houseplants in the spring (late February through April) and that is indeed an excellent period for doing the job, but you don’t need to limit yourself to those 3 months. In fact, you can repot a houseplant whenever it is in “active growth” (putting out new leaves, roots, stems or flowers).
Just about the only time when it’s best to leave your plants alone is when they are dormant or more or less dormant, usually in late fall and winter. You see, when you repot a plant that isn’t growing, it just isn’t ready to handle the sudden influx of fresh moist soil and added minerals and that can lead to root rot.
So, for many plants, consider repotting from late February through late October in the Northern Hemisphere, but not in November, December, January or early February.
That said, there is an exception. plants that grow all year long can be repotted in any season. You’ll find that many plants growing under artificial lights will grow all year and you can therefore repot them whenever you feel like it!
For a mini-course on repotting, read Repotting Boot Camp.