Preuss, 26, joined the Reds in July last year and made 17 appearances in her first season.
She arrived in England with Sunderland before making the switch to Liverpool.
Kitching, 21, graduated from the Sheffield United Academy before moving to Chelsea in 2015, later joining Watford on a season-long loan deal in 2017.
After briefly returning to the Blades, she was snapped up by Liverpool Women in August 2018, making 10 appearances in her first season.
Liverpool FC Women first-team goalkeeping coach Craig Dootson said: “It’s great news for the club and great news for me.