to arrange for an agreement or official document to continue for a further period of time
renew somebody's contract/licence/membership etc
I need to renew my passport this year.
to begin doing something again after a period of not doing it [= resume]:
Local people have renewed their efforts to save the school.
Police renewed their appeal for witnesses.
renew a friendship/acquaintance etc (=become friendly with someone again)
to remove something that is old or broken and put a new one in its place [= replace]:
The window frames need to be renewed.
to arrange to borrow a library book for a further period of time