session destrioyed on add to cart in laravel - laravel-5

Question

I am using laravel5. I need to add the product into cart. when i add a new product it is add into cart item as 1. but when refresh the page or move to next page my cart item count destroyed. Here i attach my coding. Please help me what is my mistake. i am new to laravel
Controller:
public function cart($request)
{
$quick=Mainpage::get_quick(5);
$logo = Mainpage::get_image();
$result_cart = Mainpage::get_add_to_cart_details();
$session_result = '';
// if(Session::get('cus_id'))
// {
// $navbar = View::make('layout.header');
// }
// else
// {
// $navbar = View::make('layout.header');
// }
return view('cart', ['logo' => $logo, 'quick' =>$quick,'session_result'=>$session_result,'result_cart'=>$result_cart]);
}
Model:
public static function get_add_to_cart_details()
{
$get_pro_dea = "";
if(isset($_SESSION['cart'])){
$max=count($_SESSION['cart']);
for($i=0;$i<$max;$i++){
$pid=$_SESSION['cart'][$i]['product_id'];
//$pname="Have to get";
$get_pro_dea[$pid] = DB::table('le_product')->where('product_id',$pid)->get();
}
}
else
{
$get_pro_dea[0] = array();
}
return $get_pro_dea;
}
View:(header.blade.php):
<div class="col-sm-4" style="margin-top:17px">
<div class="cart box_1 pull-right">
<a href="<?php echo url('cart'); ?>">
<?php if(isset($_SESSION['cart']))
{
$item_count_header1 = count($_SESSION['cart']);
}
else {
$item_count_header1 = 0;
}
$item_count_header = $item_count_header1;
if($item_count_header != 0)
{
?>
<img src='<?php echo url(); ?>/assets/images/shopping-cart.png' alt=''><span style='color:black;
'> ( <?php echo $item_count_header; ?> Items) </span>
<?php
}
else
{ ?>
<img src="<?php echo url(); ?>/assets/images/shopping-cart.png" alt=""><span style="color:black;"> (card empty)</span>
<?php }
?>
</strong>
</a>
</div>
</div>
</div>
<?php } ?>
</div>