I'll check to see which channel will show these as each comes up. Last season some preseason matches were shown on NESN.
Liverpool’s pre-season programme
July 7, Chester City @ Swansway Chester Stadium (Live on LFCTV GO) 10 AM Eastern
July 11, Tranmere Rovers @ Prenton Park (Live on LFCTV GO) 2:30 PM Eastern
July 14, Bury @ Energy Check Stadium (Live on LFCTV GO) 10 AM Eastern
July 19, Blackburn Rovers @ Ewood Park (Live on LFCTV GO) 2:45 PM Eastern.
July 22, Borussia Dortmund @ Bank of America Stadium, Charlotte, North Carolina--ESPN-- 4PM Eastern
July 25, Manchester City @ MetLife Stadium, New Jersey-- ESPN2-- 8PM Eastern
July 28, Manchester United @ Michigan Stadium, Ann Arbor, Michigan--ESPN-- 5PM Eastern
August 4, Napoli @ Aviva Stadium, Dublin (Live on LFCTV GO) 1PM Eastern
August 7, Torino @ Anfield (Live on LFCTV GO) 2:30 PM Eastern
But if you don't want to hassle with scrambling for a poor quality stream, you can always sign up for LFCTV for a month.