What are the preservatives? If it has sorbate you won't be able to get a fermentation going, if it has sulfites, you should be fine. I don't think there is sorbate in this, I have used a generic Real Lemon concentrate before for Skeeter Pee and it worked.
Do you understand what a slurry is? When you make a wine and rack from the primary to a secondary, what you have left behind in the primary is your slurry. A slurry is the yeast that has eaten it's fill and has dropped to the bottom of your primary.