If you're a chronic slicer, chances are you're not releasing the clubhead through impact. One of the most common flaws that keeps a player from releasing the clubhead properly is allowing your left arm (for right-handed golfers) to extend away from your left side through impact.
Here's a great drill to fix that swing flaw-stop by the range at any PGA Tour event and you'll be likely see a number of pros using this practice technique.
With a 7-iron, hit a few practice balls with a towel or headcover under your left arm.
After impact, make sure that your left arm stays "connected" to your left side.
You'll know your doing it correctly if the towel or headcover stays under your arm. You'll feel your right arm rotate powerfully over your left through the hitting zone.
If the towel or headcover falls to the ground, you've allowed your left arm to move away from your body through the ball, causing you to "hang on" to the club rather than releasing it. (You've probably seen Tour players intentionally allow their left arm to fly away from their body on occasion. This keeps the clubface open through impact, which allows them to hit an exaggerated cut shot.)
If you get a case of the "high rights" and it feels as though you're making a weak, all-arm swing, start by double-checking your release. A couple of practice swings with a head cover under your left arm might be all that it takes to plug your power leak.