In my opinion by diversification: by offering a range of leisure facilities, gastro pubs and restaurants, cinemas, and children's play areas. There was a temporary sand-pit for children in an unused shop unit in Tower Ramparts until recently. The provision of a leisure facility in a shopping mall increases 'dwell time', increases both the spend and the happiness factor. People feel good when engaging in, or planning to participate in the leisure offering.
Since 1990 the standard leisure offer in a shopping complex has been a cinema, in out-of-town retail parks these are multi-screen venues. This is the sort of provision that was planned for the Buttermarket centre in Ipswich. The anchor store is currently empty, but has been Owen Owen, Allders, and TJ Hughes. It was to be converted into a nine screen Vue Cinema supported by restaurants. The operator became nervous when the five screen Odeon in St Helens Street was sold recently with the potential of overprovision of cinemas in town.
Westfield Shopping at White City to the west of London is experimenting with KidZania, an education and entertainment complex, adult style role-play situations that apparently children love. To enjoy the games and rides inside KidZania, visitors have to pay using the 'KidZo' (local currency). They get 50 KidZos on entry and have to budget their stay to enjoy the facilities to the full. To make the visit even more life-like they don't carry cash (KidZos) but deposit them in the bank and receive a credit card that only they can use. Nobody else in the KidZania can spend their KidZos.
The other leisure provision that seems to work in retaining the public in town are roof gardens, particularly when available for a picnic or just looking at the view. Sometimes roof gardens can become skate parks and roller-skating rinks.