Manual excerpt length on recent posts slider

The line below the one you edited computes the edited words based on the height and width of the slider box. The value you added is changed on the next line. Avoid editing the plugin file. Next time you update the plugin your changes will be lost.

You should be able to change the Excerpt length on the plugin options page on the Excerpt Words option. Apparently, the Excerpt Words option overrides the computed $excerpt_length value.