I hear a lot of Confessions. Not that I am complaining (at least most of the time). And it really heats up during Lent and Holy Week. I hear 3 to 5 hours a day during Holy Week. I want to ensure that there is no excuse for not going to Confession before Easter. (It also has the added benefit of annoying the liturgists. This is always a plus.)
One thing that I hear over and over again is people apologizing for confessing the same type of sin over and over again. First of all, let me assure you that we priest don't grade you on originality. We really don't want you to come up with new and original sins or combination to keep us entertained. Anyways, after 15 years I think it would be difficult to come up with something I haven't heard. Off the top of my head, I think the only things I am missing on my checklist are cannibalism and kidnapping.
Second, it is important to realize that most people do confess the same type of sin over and over again. It is not because they are not, with God's grace, working on conversion. It is because our characters are fairly fixed and rarely change. And the devil attacks us precisely where we are weakest. Is it any wonder that that is where we sin.
So don't give up! Keep working with God's help on strengthening those weak areas and don't worry about boring the priest.