The risk in trying to use wild yeast is there is no telling how strong it will be. You need to be just as sanitary as with any other brewing, so that bacteria can't take over before the wild yeast can. Also, adding sugar will not help the fermentation, it is only used to up the alcohol level and perhaps made it go a bit dryer. I don't have much experience with mold, so I would wait for more experienced brewers to step in. But, if it was me, I would rack your juice out of the carboy (is it in a carboy, bucket or a jar?) leaving the mold behind. I would then add 1 crushed campden tablet per gallon, wait 24 hours and pitch a packet of dry brewer's yeast. Hopefully if you get it off the mold quick enough, you will be able to get a new yeast going and save this.
Hopefully someone like yooper or solstice or somebody will confirm, deny my idea.