I had white lines on the side of my tongue and I went to get a biopsy done and they said no kind of abnormal cells were dividing or were present, so does this mean I'm good to go or should I get another biopsy? I got the biopsy on the white line on my tongue about 2 or 3 weeks after they first appeared. They have still not gone away. The dr said it was leukoplakia from chronic irritation. I don't get it.

Here is some good info about leukoplakia

Don't worry about another biopsy if the appearance of the white patch isn't changing. It is an area of the mouth that should be looked at closely for changes at every dental visit.