Can you let me know how many times can a knee ligament be repaired before you consider knee replacement?

Not enough info: This is a difficult question to answer without more information. If you have a bowed-leg (varus) arthritis, the ligament reconstruction, if it's an acl will most always fail unless your alignment is corrected with an osteotomy. Multiple reconstructions will only lead to a stiffer joint with increased scar tissue and the results on a total knee will be will be worse because of limited motion range.