I have a bad cycle do you think Allah can forgive me?

I promised Allah many times that I won't do it but I kept doing it but I believe it's one of the major sins I realy want Allah to forgive me I do not to be punished in the grave or after I die I will do anything I realy want help do you think Allah can forgive the major sins even they are repeated I promise 70 times I won't do it agin or do you think Allah is just going to ignore me I want him to hear me and I will be a good slave of him I will stop this major thing please help me I don't want to be ignored I want Allah back! Please do you think he will forgive me am only 13 years old and I will try to take the evil away!