How do you fix a slice in golf?
I think that giving up the game is the only sure thing.
That said, a slice generally is caused by the clubface being open at impact. Conversely, a hook is caused by the clubface being closed at impact.
How do you cure it? Lessons. Practice. More lessons. And more practice. And even that likely won’t be enough. The slice keeps the entire golf teaching industry employed.
I came across this video a couple of weeks ago and it has dramatically helped me with my slice.
http://www.purepointgolf.com/forums/entry.php?90-Killing-Your-Slice