You must take additional science courses and perform much better. Before taking additional science courses, you must identify the factors that worked against your success in previous courses. If you need help with study habits, with time management, or with test anxiety, you can consult a learning resource specialist. While you're still a Penn student, you can seek help from the Learning Resources Service of the Department of Academic Support Programs. Once you're ready to take additional courses, you have a number of options to consider.
Some programs lend themselves more to applicants with particular needs and strengths.
You can consult a Pre-Med Advisor for help in deciding among the options. Clearly, the fastest way to improve your science average is to take science courses on a full-time basis. That option may not be practical for you. Some applicants discover that they can gain part-time tuition benefits from their employers. A number of universities offer this benefit for full-time employees.