sich etw. entgehen lassen - to miss sth.; to let sth. slip through one's fingers [fig.]
Das ganze Geld rinnt durch seine Finger. - All the money slips through his fingers. Schade, dass du dir diese Party hast entgehen lassen müssen. - It's a pity that you had to miss this party! Lass dir die Gelegenheit nicht entgehen! - Don't let the chance slip away/by!