There are a few ways to repot a snake plant with fungus gnats. 1. One way is to put the plant in water that has been heated to boiling. 2. Another way is to put the plant in a pot with some strong rooting hormone. 3. Make sure the soil is free of rocks and other obstacles. Rocks can hold water and fungus gnats, which can cause damage to your snake plant. 4. Add a nutrient mix to the soil before adding the plants. Nutrients help to improve growth and reduce problems with pests and fungus gnats. 5. Keep an eye on the plants when they are new - if they show any signs of distress, take them down for repotting. If your snake plant begins to produce flowers or fruits at an unusual time, that may be a sign that something is wrong with its soil quality.