Не изменяются вообще? При удалении? При добавлении?
Не имея всего кода отлаживать невозможно.
Вот такой простой пример перенумеровывает строки в таблице
<html>
<head>
<meta http-equiv="Content-type" content="text/html; charset=utf-8" lang="ru">
<meta name="viewport" content="width=device-width, initial-scale=1.0" >
<title>TEST</title>
</head>
<body id="body" >
<table id="parentId">
<thead>
<tr>
<th>№</th>
<th>Номенклатура</th>
<th>Кол-во</th>
<th>Цена</th>
<th>Сумма</th>
</tr>
</thead>
<tr>
<td><input type="number" value="1" name="str[]" readonly></td>
<td><input type="text" class="form-control" id="name" name="name[]" required></td>
<td><input type="number" class="form-control num" id="num" name="num[]" value="" required></td>
<td><input type="text" class="form-control price" id="price" name="price[]" value="" required></td>
<td><input type="text" class="form-control sum" id="sum" name="sum[]" value="" readonly></td>
</tr>
<tr>
<td><input type="number" value="1" name="str[]" readonly></td>
<td><input type="text" class="form-control" id="name" name="name[]" required></td>
<td><input type="number" class="form-control num" id="num" name="num[]" value="" required></td>
<td><input type="text" class="form-control price" id="price" name="price[]" value="" required></td>
<td><input type="text" class="form-control sum" id="sum" name="sum[]" value="" readonly></td>
</tr>
<tr>
<td><input type="number" value="1" name="str[]" readonly></td>
<td><input type="text" class="form-control" id="name" name="name[]" required></td>
<td><input type="number" class="form-control num" id="num" name="num[]" value="" required></td>
<td><input type="text" class="form-control price" id="price" name="price[]" value="" required></td>
<td><input type="text" class="form-control sum" id="sum" name="sum[]" value="" readonly></td>
</tr>
<tr>
<td><input type="number" value="1" name="str[]" readonly></td>
<td><input type="text" class="form-control" id="name" name="name[]" required></td>
<td><input type="number" class="form-control num" id="num" name="num[]" value="" required></td>
<td><input type="text" class="form-control price" id="price" name="price[]" value="" required></td>
<td><input type="text" class="form-control sum" id="sum" name="sum[]" value="" readonly></td>
</tr>
<tr>
<td><input type="number" value="1" name="str[]" readonly></td>
<td><input type="text" class="form-control" id="name" name="name[]" required></td>
<td><input type="number" class="form-control num" id="num" name="num[]" value="" required></td>
<td><input type="text" class="form-control price" id="price" name="price[]" value="" required></td>
<td><input type="text" class="form-control sum" id="sum" name="sum[]" value="" readonly></td>
</tr>
</table>
<script>
function repos () {
var rows = document.getElementById('parentId').tBodies[0].rows;
var i
for (i = 0; i < rows.length; i++) {
rows[i].cells[0].children[0].value = i+1;
}
}
repos()
</script>
</body>
</html>