A fairly common scenario is that you're on a medication that works well initially, but after a while, it works less, and ultimately stops working.

This can occur with any medication, including antidepressants. The normal maneuver is to either raise the dose, switch, or augment it with some other medication. It is also why I have always advocated getting off these medications when you feel well again (although the APA Guidelines suggest at least 4-6 months of continued treatment after you...