Answers
I keep falling into the same sin.
Repentance that works is specific and structural, not emotional. Name the sin exactly. Cut the supply line — the device, the route home, the contact, the hour of the night — because Jesus spoke about amputation for a reason. Tell one mature believer and give them permission to ask you weekly; secrecy is the oxygen. And if what you are fighting is a genuine addiction, get proper help as well as prayer; God works through doctors and counsellors, and asking for that is not a failure of faith.
Go and see for yourself
And if thy right hand offend thee, cut it off, and cast it from thee: for it is profitable for thee that one of thy members should perish, and not that thy whole body should be cast into hell.
Matthew 5:30
Confess your faults one to another, and pray one for another, that ye may be healed. The effectual fervent prayer of a righteous man availeth much.
James 5:16
There hath no temptation taken you but such as is common to man: but God is faithful, who will not suffer you to be tempted above that ye are able; but will with the temptation also make a way to escape, that ye may be able to bear it.
1 Corinthians 10:13