When you use
$('.pickDate').datepicker()
it is assigning datepicker to every element found that time, but not for every time in the future. In order to provide this functionality to your created inputs, wrap them in a jquery object, and individually assign the datepicker to them in your function
function addNew() {...
var newDate = document.createElement('input');
newDate.type = "input";
newDate.id = "date";
newDate.className = "pickDate";
$(newDate).datepicker();
.....}
or to leverage jquery more
var count = 0;
function addNew(){
var newDate = $('<input type="input" id="date'+(count++)+' "class="pickDate"').datepicker();
}
Note: id
is meant to be unique, so it should really have some sort of offset if you are creating multiple ones (probably not just an int, this is just to show the concept)