Try the solution by @Pieter Goosen i found for me it was the best solution, and it easy to customise.
if ( ! function_exists( 'pietergoosen_custom_wp_trim_excerpt' ) ) :
function pietergoosen_custom_wp_trim_excerpt($pietergoosen_excerpt) {
global $post;
$raw_excerpt = $pietergoosen_excerpt;
if ( '' == $pietergoosen_excerpt ) {
$pietergoosen_excerpt = get_the_content('');
$pietergoosen_excerpt = strip_shortcodes( $pietergoosen_excerpt );
$pietergoosen_excerpt = apply_filters('the_content', $pietergoosen_excerpt);
$pietergoosen_excerpt = str_replace(']]>', ']]>', $pietergoosen_excerpt);
//Set the excerpt word count and only break after sentence is complete.
$excerpt_word_count = 75;
$excerpt_length = apply_filters('excerpt_length', $excerpt_word_count);
$tokens = array();
$excerptOutput="";
$count = 0;
// Divide the string into tokens; HTML tags, or words, followed by any whitespace
preg_match_all('/(<[^>]+>|[^<>\s]+)\s*/u', $pietergoosen_excerpt, $tokens);
foreach ($tokens[0] as $token) {
if ($count >= $excerpt_word_count && preg_match('/[\?\.\!]\s*$/uS', $token)) {
// Limit reached, continue until ? . or ! occur at the end
$excerptOutput .= trim($token);
break;
}
// Add words to complete sentence
$count++;
// Append what's left of the token
$excerptOutput .= $token;
}
$pietergoosen_excerpt = trim(force_balance_tags($excerptOutput));
$excerpt_end = ' <a href="'. esc_url( get_permalink() ) . '">' . ' » ' . sprintf(__( 'Read more about: %s »', 'pietergoosen' ), get_the_title()) . '</a>';
$excerpt_more = apply_filters('excerpt_more', ' ' . $excerpt_end);
//$pos = strrpos($pietergoosen_excerpt, '</');
//if ($pos !== false)
// Inside last HTML tag
//$pietergoosen_excerpt = substr_replace($pietergoosen_excerpt, $excerpt_end, $pos, 0);
//else
// After the content
$pietergoosen_excerpt .= $excerpt_end;
return $pietergoosen_excerpt;
}
return apply_filters('pietergoosen_custom_wp_trim_excerpt', $pietergoosen_excerpt, $raw_excerpt);
}
endif;
remove_filter('get_the_excerpt', 'wp_trim_excerpt');
add_filter('get_the_excerpt', 'pietergoosen_custom_wp_trim_excerpt');