$15k is a lot of money, and that's an incredible streak to go from $200 to $15k in a day, but you better be careful, because you can lose it just as fast as you just made it. Just don't get cocky now. I'd strongly consider playing lower. Also, you are going to have trouble withdrawing that kind of money and not paying taxes. Start keeping up with your sessions. If you get audited, you could be fucked if you don't.
And also, be aware that the US shut down the three biggest online poker sites for US players back in April. Only 1 of the sites has given players their money back, and it is uncertain whether the other 2 will give the money back at all. Under the current legislation, Bodog could be shut down any day, and your money could be locked up for months, or worse, you could not get it back at all. You seriously may want to say, hey I just got really lucky and made a quick $15k. Now I'll take a vacation, buy a flat screen, and put the rest in the stock market as a good start to my savings.
Whatever you do, unless you think you can become a professional poker player, don't let this easy money ruin your work ethic or value of money. It'll probably take you 6 months of hard work to get $15k after tax money after college. Even professional players go through massive swings like this. Tom Dwan has won $2 million in a session, but also lost $5.5 million in one week, which then took him a year to come back from. No matter how much money you have, you can go broke if you aren't careful. Well, that's enough of a lecture. Have fun and good luck. I hope you keep winning!