What Else Besides Knee Brace Can Help With Torn ACL?

I'm 14 years old and I've completely torn my ACL last year. I wear knee brace everytime I do sports but the brace is kind of old so it's not really effective. Even though I wear that brace I can feel my knee giving up sometimes. I have no confident on fast running or running for more than 1km and so is my mom. Is it ok for me to run that long? how about 3km? I'm not really atheletic, either.