If you want to repopulate the Repeater, you can do this:
$w(" #repeaterX “).data = ;
$w(” #repeaterX ").data = newData;
The onItemReady() function is not triggered for existing items that are updated when you set the data property. By first setting to an empty array, it forces the Repeater to completely re-render with the onItemReady() function.
The other option is to call forEachItem() after setting the data property.