複製產品時如何將原本的時間改為現在的時間？

如果原來的產品是2014-04-28 00:00:00
複製時也會保留2014-04-28 00:00:00
如何將date_added改為現在的時間2015-04-28 00:00:00？

因為是copy所以所有資料都必須一樣的

我查了copy function,也沒有修改日期的代碼

public function copy() {
$this->language->load('catalog/product');

$this->document->setTitle($this->language->get('heading_title'));

$this->load->model('catalog/product');

if (isset($this->request->post['selected']) && $this->validateCopy()) {
foreach ($this->request->post['selected'] as $product_id) {
$this->model_catalog_product->copyProduct($product_id);
}

$this->session->data['success'] = $this->language->get('text_success');

$url = '';

if (isset($this->request->get['filter_name'])) {
$url .= '&filter_name=' . urlencode(html_entity_decode($this->request->get['filter_name'], ENT_QUOTES, 'UTF-8'));
}

if (isset($this->request->get['filter_model'])) {
$url .= '&filter_model=' . urlencode(html_entity_decode($this->request->get['filter_model'], ENT_QUOTES, 'UTF-8'));
}

if (isset($this->request->get['filter_price'])) {
$url .= '&filter_price=' . $this->request->get['filter_price'];
}

if (isset($this->request->get['filter_quantity'])) {
$url .= '&filter_quantity=' . $this->request->get['filter_quantity'];
}

if (isset($this->request->get['filter_status'])) {
$url .= '&filter_status=' . $this->request->get['filter_status'];
}

if (isset($this->request->get['sort'])) {
$url .= '&sort=' . $this->request->get['sort'];
}

if (isset($this->request->get['order'])) {
$url .= '&order=' . $this->request->get['order'];
}

if (isset($this->request->get['page'])) {
$url .= '&page=' . $this->request->get['page'];
}

$this->redirect($this->url->link('catalog/product', 'token=' . $this->session->data['token'] . $url, 'SSL'));
}

$this->getList();
}

admin/model/catalog/product.php
public function copyProduct
應該是這個喔！不過不知道怎麼修改

我也查了這個function,這個function並沒有代碼修改時間的