As someone who has been a career slicer of the ball, i know how you feel.
I have managed turn my slice into a manageable little fade. I found the following instrumental in stopping the dreaded slice.
1. Alignment - Make sure your feet and shoulders and properly lined up, many slicers have they're shoulders pointing left, personally i have to really push out my left shoulder on address.
2. Swing plane - On your back swing try to take the club slightly inside, this will promote a draw shape to combat the accentuated fade shape.
3. Grip - many slicers grip the club too hard, relax that grip, personally i changed to a baseball grip, although i'm not saying grip type is relevant slicing.
4. Relax - Slicers find themselves in a vicious circle, they're anxious about slicing the next shot, therefore are tense rigid on address, this is counteractive to hitting good shots.
5. You can try addressing the ball with an open stance as if you're feet are aiming slightly right of the target, aim your club at the target and swing along the line of your feet.
6. Swing smoothly, don't whack the hell out of it, i guarantee you the ball will travel further and straighter.
Good Luck