Thank you for your question. Frapping is unfortunately a common practice among males due to the highly sexualised world that we live in. It is a habit that needs to be dealt with in a number of ways so what follows is not an exhaustive list but some suggestions on what to do.
1) It is very important to be clear about the harms of frapping both for your current mental state and for your future life with a partner. That is aside from the effects on your spirituality and faith as well as the punishment it induces in the next world. It is impotant to think about these so that you have a clear motivation to stop.
2) Ridding your environment of all aids and prerequisites that cause frapping. Turn on the parental locks on all your devices and make a consequences on yourself for breaking this rule in any way.
3) Realizing that breaking any habit is a process but that this specific habit should never be consciously repeated. Make this a rule for yourself. If you break it don't get so down that you stop the journey.
5) Some people have recommended having a cold shower when making the ghusl after ejaculation, so as to build up an additional barrier to the act itself.
6) Although there are no specific duas i know of continual prayer is something that is absolutely necessary to reach any important goal in life.
May you always be successful