When Hollywood filmmakers find a successful formula, they can be counted on to revisit it, and that assured us of another film teaming Adam Sandler with Drew Barrymore. Unfortunately, “Blended” isn’t nearly as charming as their earlier hits, “The Wedding Singer” (1998) and “50 First Dates” (2004). In “Blended,” Barrymore plays Lauren Reynolds, a working mother recovering from a bad marriage. Sandler plays Jim Friedman, a single dad who is yet to recover from the death of his wife.