You can't redo your UGPA. Once you get a bachelor's degree, that is set in stone. Any additional coursework taken now, even if you got a second bachelor's, would not be counted in your LSAC GPA.
What do you mean supplement it? The grades will not count. The schools still want to see the transcript from a second degree, but it in no way has any bearing on your GPA. A graduate degree would probably be worth more than a second bachelor's. But neither has any bearing on your GPA.
As already noted, there's nothing you can do to change your GPA as calculated by LSAC. I don't think a second degree will help you much in terms of law school admissions. The only thing you can do is improve your LSAT score. My guess is that you'll probably need to score 160+ to get into an accredited school. The good news is that they don't average out scores anymore. Also, keep in mind that most law school apps ask whether or not you've been in law school before. It will not look good that you dropped out somewhere else so you REALLY need to focus on LSAT. Some unsolicited input- from your few posts (esp w/regard to getting a grad degree before applying to law school), I get the sense that you're not entirely sure what you want to do as a career. Have you sought career counseling/testing?