Richards joined the Stones at the age of 12 and was part of one of the most successful youth sides in recent years.
In September 2015, he started at the Stones football academy and won back-to-back National League Youth Alliance championships.
He made his first-team debut towards the end of the last season and has made ten appearances to date, starting three times.
Richards has been linked with Premier League sides Tottenham Hotspur, Brighton & Hove Albion and Crystal Palace in recent months.