Aurbere is probably the person to answer this one. I expect he can 'rebuild' his illusions again though.
Naga Sadow orchestrated multiple battles simultaneously using his illusions and Battle Meditation. When his apprentice attacked his meditation sphere, he lost concentration, which led to the Republic making a swift counterstrike that utterly crushed Sadow's forces. Take in mind that he was also fighting Ludo Kressh's followers at the same time.
"Here in my Meditation Chamber I can see the galaxy in my mind's eye... I can visualize vast armies, powerful fleets, invincible warriors... and with Sith arts, my imagination can make them real."
In short, Sadow can produce real forces just by imagining them. These illusions are actually capable of doing real damage to enemy troops. Unless Kaan can find Sadow's sphere, he will lose. I consider Naga Sadow something akin to an Infinite Empire, if you catch my drift. He can create a limitless supply of soldiers, fleets, anything.