before after refreshing countdown didn't showed up and its goes disabled

when I refresh the page my countdown timer works perfectly, but when I refresh only particular div my countdown wont show up and button gets disabled.

note: I useed disabled tag to disabled my button

function refreshDiv() {
  $('#container3').load(window.location.href + " #container3 >");
}

JavaScript

var spn = document.getElementById("count");
var btn = document.getElementById("btnCounter");

var count = 2; // Set count
var timer = null; // For referencing the timer

(function countDown() {
  // Display counter and start counting down
  spn.textContent = count;

  // Run the function again every second if the count is not zero
  if (count !== 0) {
    timer = setTimeout(countDown, 1000);
    count--; // decrease the timer
  } else {
    // Enable the button
    btn.removeAttribute("disabled");
  }
}());

this is my html code its work properly when I refresh the whole page but when I refresh #container3 my button got disabled and countdown didn't showed

  <div class="container2" id="container3">
    <h4 id="title">here</h4>
    <div class="controls">
        <div class="main-controls">
            <div class="dropdown">
                <button
                    class="btn btn-primary dropdown-toggle" 
                    data-bs-toggle="dropdown"  id="btnCounter" disabled
                >
                    File <span id="count"></span>
                </button>
                <div class="dropdown-menu">
                    
                    <button id="txt-btn" class="dropdown-item" 
            onclick="refreshDiv();">
                        Save here
                    </button>