I disagree with Polly Mer that a 3.6 is "embarrassingly low" (it's close to an A- average), unless you are at an institution with rampant grade inflation. Whether it is attainable or competitive is another matter.
Daniel von Flanagan has given some good guidance in this area - you will have to work exceptionally hard, and may need to take more units than you have in the past (which itself may may it more difficult for you to get top grades in all of your classes). If, as DvF notes, you would be able to replace grades in classes you re-take, then this strategy could provide more bang for your buck, assuming you have reason to believe your second attempt will be much more successful than your first.
Depending on your financial considerations, interests, and the school's policies, you could also consider staying for an extra semester, or taking additional undergraduate classes at a local community college (particularly in areas relevant to business or to your major, if your major is related to the type of business you want to do).
Also, the Anderson School of Management claims that no work experience is required for admission; however, 98% of its students
did have prior work experience, and 94% had at least 2 years of work experience (with the average student having more than 4 years of experience), if I am reading the 2009 profile correctly. (
http://www.anderson.ucla.edu/documents/areas/prg/mba/profile.pdf). You may want to keep this in mind as you figure out your post-college plans.
You should certainly focus on bringing up your GPA through your upper-division coursework if your goal is ultimately to be admitted to a graduate program, but as San Joaquin and Polly Mer have noted, you should be careful not to do it at the expense of everything else that might make you a competitive candidate - good internships (which may provide a foot in the door to a good position or yield good letters of recommendation), involvement in extracurricular activities that highlight your initiative and ability to follow through on a good idea, and so on.
Oh, and aim for a great score on the GMAT.
Good luck!