I try not to take breaks, but if i did- 100% restart... I can't afford to jeopardize my game experience by not remembering the plot!! But i have bad memory issues, so maybe I'm biased?
honestly, routes are really long so if i had to restart from the common route since i came back from a long break, i would 100 percent be likely to be annoyed, but if i have a save from the beginning of the route i'm currently on, i'd replay that to where i was originally at