Once you make a good Confession, your sins are absolved forever. Your sins can’t be “unabsolved”. The addiction can still remain, which is why you may commit the sin again.
There have been lots of threads on this topic of masturbation and pornography that I invite you to search and look through. You will get great ideas and information. Here’s one to get you started:
It sounds like you are already taking some good steps, but here’s some additional thoughts:
Avoid the occasion of sin. Don’t even put yourself in an environment where you’ll know you’ll sin. Ex: keep the computer in a public place, when using the internet, have a set to-do list of what you are doing on the internet. As soon as you finish immediately shut down the computer, etc. If you tend to masturbate in the shower, maybe take cold or lukewarm showers.
Get help. Get a spiritual director or join a group. Going to confession is a great start, but its helpful to have a regular confessor that you are constantly working with. Ask your local priest, if he can’t be your spiritual director, ask him if he could refer someone to you. If you can speak to him in private, explain the situation and ask if he has any advice, or can refer you to a support group.
Pray. Pray the rosary every day. Spend some time in front of the Blessed Sacrament every day. If you aren’t constantly striving to overcome it, you won’t. Especially pray a lot to the Blessed Mother. She is a warrior when it comes to battling impurity and she will not abandon you. There is no better example of purity than her.
Read. Reading is helpful because it helps to retrain your imagination to think of other things besides impure thoughts. Read books on battling impurity, on the saints, on increasing your spiritual life, scripture, etc. You can even just read books for fun.
Find an accountability friend. Spiritual directors are great, but you also need someone you can contact on a regular basis. Someone you can be honest with when you fail, and can encourage you and challenge you in your struggles. It needs to be someone trustworthy, so be careful who you pick.
Hope that helps! You are in my prayers, and you are not alone. Many people have struggled with this and recovered.