Finally solved issue of reinitialization of select2 after ajax call.
You can call this in success function of ajax.
Note : Don't forget to replace ".selector" to your class of <select class="selector">
element.
jQuery('.select2-container').remove();
jQuery('.selector').select2({
placeholder: "Placeholder text",
allowClear: true
});
jQuery('.select2-container').css('width','100%');