Domain Change with New Image Sizes

Use plugin Regenerate Thumbnails to resize thumbnails.

Edit:

Try use filter “the_content” to convert in post content.

<?php

function foo ( $content )
{
    return preg_replace ('/540x287/', '525x279', $content);
}

add_filter( 'the_content', 'foo' )

Filter “the_excerpt” if need convert excerpt too.