Complex sentence: Toho had approached Anno in early 2013 to direct the reboot but initially declined to continue working on the "Rebuild of Evangelion" films, however, Higuchi eventually convinced him to accept the offer.
Split into simpler sentences: Toho had approached Anno in early 2013 to direct the reboot but Anno initially declined so that he could continue working on the "Rebuild of Evangelion" films. However, Higuchi eventually convinced him to accept the offer.