The phrase again and again
is a fair translation of the Greek καὶ ἅπαξ καὶ δίς (kai hapax kai dis), which means (literally) both once and twice.
Usage of this phrase in the Septuagint (Deuteronomy 9:13; 1 Samuel 17:39; Nehemiah 13:20; 1 Maccabees 3:30) shows that it effectively means more than once,
without specifying a particular number of times.1
18 because we wanted to come to you I, Paul, again and again but Satan hindered us.