JSFiddle - React, Tailwind, and code Playground
HTML
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<select id='sl1'>
<option></option>
<option>1</option>
<option>2</option>
</select>
<button>
+
</button>
JavaScript
$("button").click(function(){
var novoSl = $("#sl1").clone(true).insertBefore($(this));
//Agora é possivel manipular o novo select como desejar;
novoSl.find("option")[0].prop("selected", true);
})