I am in my junior year of high school and I feel my extracurriculars are not strong enough. I play club basketball, do band, did debate, some clubs, and some community service. I am interested in studying business and entrepreneurship in college so what are some other activities I can do to help my resume.
Looks like a good balanced of EC’s IMO 
Maybe start a business online and find ways to use creativity to make money, my friend is an entrepeuner as a teenager and he makes around $1200 dollars every six months
Try to find something you are extremely passionate in and found/join a club related to that. You can be more serious in that club, get a leadership position, win awards, etc.
Read the book “How to be a High School Superstar” by Cal Newport.
“The basic message of the book is this: Don’t wear yourself out taking as many classes as you can and being involved in every club and sport. Instead, leave yourself enough free time to explore your interests. Cultivate one interest and make it into something special that will make you stand out among the other applicants and get you into the toughest schools, even if your grades and scores aren’t stellar. Newport calls this the “relaxed superstar approach,” and he shows you how to really do this, breaking the process down into three principles, explained and illustrated with real life examples of students who got into top schools: (1) underscheduling—making sure you have copious amounts of free time to pursue interesting things, (2) focusing on one or two pursuits instead of trying to be a “jack of all trades,” and (3) innovation—developing an interesting and important activity or project in your area of interest. This fruit yielded by this strategy, an interesting life and real, meaningful achievements, is sure to help not only with college admissions, but getting a job, starting a business, or whatever your goals.”
http://www.examiner.com/review/be-a-relaxed-high-school-superstar