How to over-ride a file in a plugin? [closed]

Question

I have a third party plugin that I'm using for a photo gallery (NextGen). However, with my black background, the loader gif animation looks pretty bad. I found a better loader gif and replaced the one from the plugin. I already know this is not ideal because the next update of the plugin will overwrite my custom gif.

The gif is located at: /wp-content/plugins/nextgen-gallery/images/loader.gif

Is there a clever way to leverage my child theme's functions.php file to tell this plugin to use a different URL for the gif?

As far as using my child theme's CSS to override, that would be easiest if it was a viable option. However, the loader's URL is not coming from the plugin's CSS file.