that's know annoyance ("feature") of repeating section.

you have to assign event handlers after every new row is created.

 NWF.FormFiller.Events.RegisterRepeaterRowAdded(function(){ArtikleNummer()}); i have added this function in the document .ready the function is trigerring but the controls are not able to bind the events

how do attach the handlers?

do you correctly reference control in current/new repeater row?

NWF.FormFiller.Events.RegisterRepeaterRowAdded (function () {
var repeaterRow = NWF$(arguments[0][0]);
//alert(repeaterRow);
repeaterRow.hasClass('Vertriebs_Artikel_Nummer_1')
{
NWF$('.Vertriebs_Artikel_Nummer_1').on("change",function(){ArtikleNummer()} );
}
});
i am using this code

is it really your whole code?

it's logically not correct at all....

have a look eg. here how to correctly attach a handler to a control within repeating section https://community.nintex.com/message/52309-re-autocomplete-in-a-repeating-section?commentID=52309#comment-52309