温故知新

to review the old and know the new (idiom, from the Analects); to recall the past to understand the future

to observe the past to foresee the future (idiom, taken loosely from Book of Songs); studying ancient wisdom gives insight into what is to come

don't forget past events, they can guide you in future (idiom); benefit from past experience

to learn from history (idiom)

studying the old to promote the new (idiom)

to discard the old and introduce the new (idiom); to innovate