SI is an addiction; that's why you keep adding to them. At least, that's my theory.

I haven't done that in 4 years, but I hate my scars, as well.

All I can really say to you, is that you will just keep regretting it, ... break the cycle... use that regret to STOP. The more you add, the harder it will get to get passed them. There are other, far better ways to cope with stress/emotions. I've been there, ... I know how it feels, ... I did it for years, ... I know how pointless it was because I'm still here, and I still regret every single one of them, but you know what? The reason I ever did it is still there, ... I still don't like myself, but I know now that it wasn't the answer... and it never was. All I needed to do was find a proper outlet (exercise, guitar, talking about stuff, and happy things) for how I felt, and to realise that I needn't punish myself. I guess I figured I'd punished myself enough, and not just SI. I have emotionally beat myself up for years... enough was enough.

Maybe it's time to love your body, instead of hurting it. Life is precious... every second of it. For you, and for those that care for you.