。
Once again, she was late.
Literal
Again-and-again she [topic-は] was-tardy.
又しても ('again and again,' 'yet again') is an emphatic adverb meaning 'yet another time' — usually with a slightly exasperated or critical tone about repetition. 遅刻する ('to be late [for a scheduled thing]') is specifically about being late to work, school, or appointments — distinct from 遅れる (more general 'be late').