How to get rid of gnats who took residence in my houseplant?

I bought this little spider plant at a church sale about 10 years ago and somehow it has survived despite my occasional negligence when I was younger.





I recently discovered gnats living in the soil, so I threw out the soil, put the plant in a vase of water for a week outside. I got new potting soil, re-planted and two weeks later I found gnats in the soil again.





Is there any solution to this? I know they have preen that kills weeds and doesn't harm plants, but is there a similar product for getting rid of bugs?





I honestly love this plant so any advice would be welcome.





Thanks!

How to get rid of gnats who took residence in my houseplant?
The bugs are fungus gnats. They are there because the soil is too wet and the roots may be beginning to rot. Set the plant in the sink and remove the drain tray to drain as much water as possible. Then do not water the plant till the soil feels very dry. Just drying out the soil will get rid of the gnats if you can be patient. If not put some rubbing alcohol in a spray bottle and spray the surface of the soil with it. You will kill any fungus gnats that it hits on contact. But that is only a temporary fix. Keep your plant dryer and they will go away. Two hours after you water your plants dump the water out of the drain tray so the plants are not sitting in water and they are less likely to be over watered. More plants are killed by too much water than by too little! Good luck.
Reply:I found some good advice on fungus gnats at Cornell Cooperative Extension there are 2 pdfs you can look at with good information---Cornell Cooperative Extension (Nassau County) New York
Reply:nother thing is to mix dawn dishwashing liquid or really any kind with water 4/1 ratio and spray it on the soil and plant it will get rid of them , it sounds like soil is too moist and not enough sun where you have the plant.