Boredom is one of two things, happily neither of which cost a penny to fix: anger or confusion.
A period of confusion at around 14 is normal. Being 14 is hard. There are a lot of brain changes that stop children from being able to think they way they used to, but haven't yet completed their growth to enable to think they way they will be able to. They go between feeling totally incapable of dealing with the inside of their own heads and feeling suddenly capable of all kinds of things they don't know how to do. It's hormonal, which is difficult enough to live with, and a result of physical brain changes that no one is in control of. Basically, they feel frighteningly out of control, lost, alone and misunderstood (because they don't understand themselves)...
The other cause of boredom is anger. Feeling oppressed (which has nothing to do with the rest of her life, it's a feeling, not a reflection of reality, necessarily), feeling restricted (ooh, the restrictions 14yos have!) and feeling disempowered all lend themselves neatly to 'boredom' based on rage. The child is often in a furious state, but can't identify what is making her angry... so she complains about things that often don't matter that much to her, or she whines about how her life isn't entertaining her the way it's supposed to.
She may, in fact, be angry about how confused she feels.
Whatever she's feeling, what she needs is her home and family to be a safe place where she doesn't have to defend herself, justify herself or protect herself from criticims or heckling. She needs her mom to put her arm around her shoulders and tell her how beautiful she is, how mature she is compared to last year, how much time she has before she is required to make a final decision about the rest of her life, and how loved she is. She needs affection, security and a sense of personal power that is not overwhelming to her (the huge range of possible choices that she is suddenly capable of perceiving is pretty overwhelming without the added pressure of mom and dad asking her what she's going to do with the rest of her life)... she needs to be protected from her inabilities and trusted to develop them into abilities over time... as her hormones and brain development settles down.
At this point, she's just flailing around her environment looking for an external 'fix' to an internal struggle. As you may have guessed from how that was worded: there isn't one.