What were the circumstances of your tear the first time around? What position were you in, did you have an epidural, did you have an episiotomy cut that tore further, were you being directed to push instead of pushing based on what your body told you, was the baby's hand or elbow up at his face so you had to push an even larger body through your vaginal outlet? These are common reasons for women to tear.
Some of this stuff, you can avoid/mitigate, some of it you can't (like nuchal hands).
If you go for a second vaginal birth,
- try to do it without an epidural as it gives you maximum control and sensation so you can move during the pushing phase and can also feel everything that's going on.
- Give birth in a gravity neutral position (hands/knees, side-lying) and DO NOT BIRTH FLAT ON YOUR BACK. Squatting I would also avoid just because it's gravity assisted, and you want the baby to come slowly.
- Try to let the baby come out SLOWLY, giving tissue time to stretch, don't try to get the baby out fast unless there's a medical necessity to do so.
- Don't let anyone touch or mess with your vagina or perineum in any way while you are pushing (though you may want to touch it to contol how fast the head crowns).
- Don't let anyone cut an episiotomy without an immediate, emergency, baby must come out NOW reason.
- Birth in water if you can.
Maybe go see a pelvic floor specialist (physical therapist or gynecologist who doesn't necessarily do OB work) if you want an assessment of the current strength of that area and a neutral party's opinion about whether it would tear so badly again. A PT might also be able to help with strengthening exercises before the birth to increase your chances for an intact pelvic floor.
Also, here's an article from Gloria Lemay on birthing with an intact perineum
I think I'd choose the unknown risk of a vag. delivery over the known risks of major abdominal surgery. Good luck making a decision.