Fungus gnats: help!

[newyorkbreakfast]

Almost all my indoor plants are affected. I've tried matchsticks in the soil, cinnamon, drying the soil out, changing the potting compost.
Is there any more I can do to get rid? It's driving me mad. I was about to repot a plant... I lifted it from its decorative pot, only for there to be yet another cloud of gnats.

Thank you - that's useful. I know I need to repot my indoor plants, but I've been putting it off for ages because I just know it will bring fungus gnats in!

Nuke it in the microwave, it's the only way to be sure!

Put a drip of washing-up liquid per litre of water in the can when you are watering. Go easy though, you don't want froth!