Cech concedes with their Champions League elimination, winning the Cup is now the only trophy left.
He wrote for chelseafc.com: "It's definitely not an easy game because for them it's a historical moment, so they will obviously go there and try to make the most of it and their fans will surely enjoy it. So we need to be prepared and we've played on many, many occasions at Wembley, and many FA Cup semi-finals overall, so we know what it takes and hopefully we can reach another final.
"Unfortunately we have a points deficit in the league table, so obviously it's going to be difficult to think about the title because it's completely out of our hands. We will need to rely on Liverpool and City to have a meltdown.
"Of course you play on that front, you play every game and you want to win every game and we want to make sure we are in the Champions League next season, but realistically, after Tuesday's loss, now the FA Cup remains the only competition we can win, so we would like to achieve that.
"We have one trophy left and, of course, after the last year with the success we've had we want to end this season on a high."