The sticky traps work great for the flying gnats, for the larvae in the soil you'll need to let the soil dry out completely, to the point where it looks like your ladies are very sad and droopy. Gnats love moist soil. This could be part of your problem as to why they aren't dying as fast. Another thing you can do is purchase a pound or two of (Sterile) Sand, and put about 1/2" to 1" on top of your soil, I would do this about 3 days after watering. The sand is too heavy and dense for the larvae to crawl out. As long as you let your soil dry out completely between watering, you'll notice more and more dead gnats.

I also use a shot glass or small lid (shallow), pour a small amount of wine or beer in the lid, set it at the base of the plant or on top of the soil. Come back the next day and you have a glass/lid full of drunken dead gnats.

Also, look up a drench solution called "Azamax". It's simple, easy, and effective. Just add the specified amount of solution to water and drench your soil with about a 1/4 run-off. Repeat this process once a week or until soil is completely dried out, for about 3 weeks. This product also fights mites/insects of all kinds as well as fungus, and mold!