In general, tearing is easier on your body that an episiotomy. Especially if you had a mild tear last time, it's more likely to be mild again or non-existent. During labor, be in warm water when you can (or have your SO hold a warm wet washcloth down there). The warmth and the water both help your tissues stretch more gradually, reducing your chances of tearing.
Maybe they can just do an episiotomy rather than risk having you tear again. Find out.
Perineal massage can help prevent tearing (I have a brief description of it on my profile under journals), as can kegal exercises. Yes you'll missy likely tear along your scat if you tear again, but since your tissues have already stretched once you're less likely to tear as badly (not that four stitches is bad! I'll trade you my third degree for your first/second degree any time!)
What are they? The least I want is to tear as well.
There's are massages, exercises and oils to help prevent taring