If a person says that he is taking an oath that he will never ever tell lies in his life and after that he tells lie 3 times, then how many times he has to pay kaffarah for his breaking oath, one time or three times ? He did not take oath again after his breaking oath for the first time.
بسم الله الرحمن الرحيم
When he took an oath that he won’t tell a lie then he must have fulfilled it. However, after telling lie first time, he will be required to pay kaffarah and the oath came to an end.
و تنحل اليمين إذا وجد الشرط مره (الدر مع الرد 5/605، زكريا)
However, it is necessary to avoid telling a lie in any case.
Allah knows Best!
Darul Uloom Deoband