Slider update() does not work

I need to interpolate like 200 items over a slider.
I just use 3 items inside the slider and i manually swap the content of those item when the change events fire.
It works but when it reaches the boundary the looped item seems a duplicate of and old item already swapped.
I tried to use the slider’s update() method but it didn’t work.

Perhaps is there a way to wait for the DOM to change before i call the update() method?