Cart: Add a Continue Shopping link
To add a custom Continue Shopping link on your cart page or cart window, here are a few modifications you can try:
Option 1 - Link back to All Products
This version will send your shoppers back to the all products page. Open your Code Editor and edit templates/cart.liquid:
https://shopify.com/admin/themes/current?key=templates/cart.liquid&line=16
Around line 16, right below the <h3> heading, add the following code:
Code to add:
<a class="{% if settings.cart_type contains 'page' %}btn btn--clear{% endif %} uppercase" href="/collections/all" title="Continue shopping">Continue shopping</a>
Example after adding code:

Save the file.
Page Cart Result:

Modal/Pop-up Cart Result:

Option 2 - Return to homepage
Use this code instead if you would like the Continue Shopping link to return to your homepage:
<a class="{% if settings.cart_type contains 'page' %}btn btn--clear{% endif %} uppercase" href="/" title="Continue shopping">Continue shopping</a>
Follow the same steps as Option 1 but use this version of the code.
Option 3 - Return to last collection viewed (Page cart only)
Note: This version only works with the Page cart type. The link will be hidden if you switch to the Modal cart type.
Step 1
Use this code instead if you would like the Continue Shopping link to return to the last viewed collection. Follow the same steps as Option 1 but use this version of the code:
{% if settings.cart_type contains 'page' %}<a id="continue-shopping"class="btn btn--clear uppercase" title="Continue shopping">Continue shopping</a>{% endif %}
Step 2
This option also requires you to add the following code to your layout/theme.liquid file:
https://shopify.com/admin/themes/current?key=layout/theme.liquid&line=999
Code to paste at the very bottom of theme.liquid:
<!-- Code used for Continue Shopping link in cart -->
<script>
if(Storage !== undefined) {
{% if template contains 'collection' %}
sessionStorage.collection = "{{ collection.url }}";
{% endif %}
if(sessionStorage.collection === undefined){
sessionStorage.collection = "/collections/all";
}
{% if template contains 'cart' %}
document.getElementById("continue-shopping").href = sessionStorage.collection;
{% endif %}
}
</script>
<!-- end -->
Save the file.
Option 4 - Go back to previous page with Page cart type
With the page cart you can use this method to have a Continue Shopping button that returns you to the last page.
Step 1 - Add one line to cart.liquid
https://shopify.com/admin/themes/current?key=templates/cart.liquid&line=16
Around line 16, right below the <h3> heading, add the following code:
Code to add:
<a class="back btn btn--clear">Continue Shopping</a>
Save the file.
Step 2
This option also requires you to add the following code to your layout/theme.liquid file:
https://shopify.com/admin/themes/current?key=layout/theme.liquid&line=999
Code to paste at the very bottom of theme.liquid:
<!-- Code used for Continue Shopping link in cart -->
<script>
$(document).ready(function(){
$('a.back').click(function(){
parent.history.back();
return false;
});
});
</script>
<!-- end -->
Save the file.