My Peperomia (which I believe I correctly identified as Peperomia albovittata, but I might stand corrected) has lost 50% of its leafage over the last 8 months.
At first it had no troubles at all, indirect sunlight, a nice spot, but then the winter came and my house can be really dark. When the leaves started to fall, I moved it to a (slightly) brighter spot. However, this wasn't enough.
You'll see from the picture, which is quite brighter than in reality, it started to lose a lot of leaves. They all start to dry off from the leaf branch toward the leaf top. Sometimes, the support is so dry the leaf falls off still looking green and succulent and shiny. When that is not the case, the leaves remain in the underbush until they are completely dried out. When I first brought it home, I couldn't see the soil in the vase.
I'd rule off repotting, as it is fairly new. I'm only watering when the soil is bone dry, leaving the pot in a basin and letting the water flow up through the soil. Right now, the top inch of the soil is completely dry (and the leaves are a little bit droopy).
Humidity in the house is around 50%. There are some new leaves sprouting, but I can reap off half a dozen leaves a week now.
What am I doing wrong?