Or when Alka-Seltzer changed their packaging: they simply removed the separator between the 2 tablets in the pouch (accompanied by a catchy new jingle). Bingo! Sales doubled.
It’s arguably harder today. Apple multiplies their sales through continuous innovation: brand new products we didn’t know we needed, followed by even better versions which bait us to trade up.
And if you’re selling advice instead of shampoo? Remove what separates you. Think about how to entangle your clients. What else do they need that you are best suited to provide? Tempt them to deepen (or broaden) their relationship with you. Surround them with appealing options to use you again.
Lather. Rinse. Repeat.