How to fulfil pre-requisite courses (no post-bacc option exist in Canada)

[pmn123]

You might have seen my other posts lately as I'm trying to figure out the best course of action for my situation. My undergrad GPA is 3.66, my law school GPA is on the B curve (I'm interested in US schools where they do not combine my undergrad with grad GPA). While I was in undergrad I took some of the pre-requisites but not all and my GPA for those science courses are low (3.3). I understand that in the US they have post-bac programs tailored for non-traditional students. Whereas in Canada such thing don't exist except two private schools in Toronto and I don't feel good about them, they look sketchy and are more tailored towards Caribbean schools. Now I want to know how I can fulfil my pre-requisites and increase my science GPA. Is doing a second degree my only hope? Do people take these courses on a part time basis as a non-degree student? What is the usual course of action for non-trads in my situation? If I can take courses as a non-degree status do schools allow you to do that? Would it be hard to get a spot in those courses? What kind of a workload should I go for (2 courses a semester or more? would one course per semester be okay?  )

Any advice would be appreciated, thank you!