Bardic Performance: A street performer gains the following types of bardic performance.
Disappearing Act (Su): A street performer can use performance to divert attention from an ally. All creatures within 30 feet that fail a Will save (DC 10 + 1/2 the bard's level + the bard's Cha modifier) treat one creature chosen by the bard as if it were invisible. This performance affects one additional creature at 5th level and every 6 levels thereafter. If the targets take any action that would cause them to become visible, they become visible to everyone. The bard cannot use this ability on himself. This ability is a mind-affecting effect that requires visual components. This performance replaces inspire courage.
Once a target of my invisibilty attacks and becomes visible, can I re-apply it to him again and opponents would have to make another DC check?
By RAW, what you would have to do on your next round is end your Disappearing Act performance as a free action and then begin another one.
This means that the creatures will get another Will save. You're essentially risking an "all or nothing" situation if you were diverting attention from more than one ally.