Spanish B or Spanish ab Initio?

So I took one year of high school Spanish a year ago. I’m good on grammar and pronunciation and etc (not future/past tense, we didn’t get to that–no advanced concepts at all), but I’ve forgotten most of the vocabulary. Is that enough for Spanish B or should I go with ab Initio?

ab initio, without a doubt

Okay, thanks. The descriptions on the signup page for my school were a bit vague.