How to keep sharing stats after creating 301 redirects?

Got it.

I was already using the Advanced Custom Fields plugin so I just created a custom field called “old_url” with that.

Then I created a function:

function sharingurl () {
    if(get_field('old_url') == "")
        {
            echo untrailingslashit(get_permalink());
        } else {                    
            echo get_field('old_url');
        }
}

Then I just included <?php sharingurl(); ?> in the data-href and data-counturl for Facebook and Twitter codes respectively.

Note: Facebook does not like trailing slashes, that’s why I had to remove it from the permalink.