raise (one's) hopes
To cause one to become excited at the prospect of something happening. If you raise Sadie's hopes about going to the carnival tonight, she'll be disappointed if we don't go. Don't raise his hopes about seeing Aunt Jen this weekend—I hear she's having car trouble.
build up/raise somebody’s ˈhopes
make somebody feel hopeful about something or persuade them that something good is going to happen: Don’t raise her hopes too much. She may not win.