I was sexually active saturday night, took plan b pill monday night, within an hour of taking the pill, was active again, can i retake plan b?

Theoretically Yes: According to the manufacturer it could be used again. However this is not birth control and is not as effective as regularly used birth control. It is also a high level of hormones. Taking it too often can add to side effects. I would recommend seeing a gynecologist to discuss your options for birth control instead of using Plan B too often.