Just practice intelligently, not sadomasochistically (sp?). Practice the fast things slowly, not painfully slowly but comfortably so that they become secure. If you always practice the hard things at Argerich tempo than you will become insecure about them, and nervous. It also helps to vary rhythms to get coordination more precicse.
I think a key component to security with repertoire is memorization. As a famous organist explained to me, there are three types of memorization, physical, mental, and aural. What it essentially comes down to is that you have to KNOW which notes follow which in the music, not just in your fingers. When you are nervous you think rapidly, and the first thing your brain thinks about is "what comes next?" and if you can't answer that question mentally, your fingers are going to panic. So study the score, and break it up into manageable subsections for reference. Even better, play it backwards, start with a final section, then play the section before it, and so on, it works wonders for memorization.
Topic: Practicing more securely!