jlt, you can just put some clones into the solo cups to sex them. They will be fine. It also doesn't really matter how good the light they are getting is. What's important is the 12 hours of dark.
Like McL said, you CAN reveg them, but it takes a month. The resulting plan will be a bush, but it takes awhile. Why would you want to do this though? If you need to grow a clone for vegging, take 2. One to grow and one to sex. Once it's sexed, let it finish for a single little nug, or just toss it. Personally, I would toss it. Keeping the plant alive in a solo cup for 3 months will be challenging.
BTW, loving all the light in that veg space. Makes my 3, and only using 2 atm, shop lights look pretty pitiful.