The former Notts County Ladies keeper, 29, rejoined Chelsea - who she played for between 2011 and 2013 - on a free transfer in May after Notts had folded.
She helped the Blues win the Women's Super League One Spring Series title in June.
Meanwhile, versatile Portugal winger Ana Borges, 27, has left Emma Hayes' side to join Sporting Lisbon.
Borges had been on loan with the Portuguese side, but has now signed a three-year contract with the club.
England goalkeeper Carly Telford has signed a new contract to stay with Chelsea Ladies until 2019.