How do I debug my plants?

I just got several plants for free to revive, two palms, two golden pothos and a spider plant. The palms have a few bugs and small worms possibly? They are in the soil and I don't have the money to go get a big bag of potting soil to do transplants right now. Is there any way I can debug the soil the plants are already in without throwing away the plants themselves? I've heard of dish soap and water mixtures but it seems that they are just for spraying the plants and not treating to soil.