themeszone

The plugin once activated will display a quantity field with increment / decrement buttons once add to cart button is pressed (e.g. the product is added to cart). 
Thus allowing customers to change the products number in the cart with out having to go to shopping cart 
page.
<a href="http://plugins.themes.zone" rel="nofollow ugc">PLUGIN DEMO</a> 
(click “Add to Cart button to see it in action”)
Feel free to ask any questions at <a href="https://themes.zone" rel="nofollow ugc">Themes Zone</a>

ThemesZone WooCommerce Ajax Quantity

ThemesZone WooCommerce Ajax Quantity Plugin shows quantity field on product listing once customer clicks "Add to Cart" button.

taisho

Adds professionally looking “-” and “+” quantity increment buttons around product quantity field on WooCommerce pages. Removes default increment arrows inside this field. Easy customization through plugin settings.
<h4>Features</h4>
<ul>
<li>Adds “-” and “+” quantity buttons around product quantity field.</li>
<li>Removes default increment arrows inside the quantity input field, which are built-in by browsers.</li>
<li>Works on product, cart, checkout, shop, category or optionally all pages.</li>
<li>Quantity field with increment buttons can be added to shop page, category page or both.</li>
<li>Should look great on most of the themes out of the box. Extensively tested on Storefront theme.</li>
<li>Fully responsive design.</li>
<li>Plugin settings allow to customize buttons.</li>
<li>Generated with PHP – visible immediately on page load.</li>
<li>Buttons are not displayed for items sold individually.</li>
<li>Compatible with Quick View plugins.</li>
<li>For automatic cart and mini-cart update after changing the quantity on the cart page, you can use my other free plugin <a href="https://wordpress.org/plugins/ajax-cart-autoupdate-for-woocommerce/" rel="ugc">Ajax Cart AutoUpdate for WooCommerce</a>.</li>
</ul>

Qty Increment Buttons for WooCommerce

Adds professionally looking "-" and "+" quantity increment buttons around product quantity field on WooCommerce pages.

ThemesZone WooCommerce Ajax Quantity vs Qty Increment Buttons for WooCommerce