Director of football Nicky Hammond told Reading's website: "He's been influential during his time with us.
"I'm sure he'll make an excellent contribution in the forthcoming season, as he did during the last campaign."
De La Cruz joined the Royals on a free transfer from Aston Villa in the summer of 2006 and included nine Premiership games in his 15 appearances last term.
Hammond added: "I went to see him play for Ecuador against Peru in Barcelona last week.
"Even though it was an end-of-season friendly he was still showing a great attitude and working hard up and down the pitch.
"That illustrates the level of his professionalism and the kind of player he is."