I know what you mean. I've had this once (about a year ago). It was a big fight! It was 4 or 5 tiny little spiders. after a week, in wich twice a day I cleaned the webs from the plant and hunted those little busters with water and pillers. I killed them all, cleaned the last remains and It was alright. The plant lives today in the same soil.
Just hunt them every day, and after a while they'll be gone (after you'll kill them all).