Undisable disabled days in jQuery datepicker

I want to un-disable dates in the datepicker, I tried to empty the array of the disabled days, but they are still disabled when I open the datepicker.

Here is my code to disable the days in the datepicker:

$('#startDate').datepicker({
                beforeShowDay: function(date) {
                    var day = date.getDay();
                    var string = jQuery.datepicker.formatDate('dd.m.yy', date);
                    return [disabledDays.indexOf(string) == -1];
                },
                minDate: 0,
                dateFormat: 'dd.m.yy',
            });

I also tried to add a random number respecting the format, but that didn't change anything.

Maybe there is a way to re-enable the dates or to reinitialize the datepicker so that there are no more disabled dates, but I'm not sure at all.