Keep track of the services and treatments your clients have had, this is easily done in Platinum at the click of a button. If you realise that some are always only booking in for a hair cut as example - target them with other treatments, for example send them a discount for a colour or if you do beauty as well, a facial.
The same if you are a beauty salon, if a customer only has facials, offer a discount for waxing... the options are endless.
You should consider doing this fairly frequently, maybe every 3 months at least. Your existing clients will invariably spend more money in your salon, plus your client base will also grow.
The clients build up points every time they spend money in your business. They will also get the opportunity of bonus points on double points days, for referring friends etc.
Instead of offering the normal, use loyalty points on anything in the salon, Let them be rewarded with services and products they have NEVER had before, opening them up to other services/products in your business.
This is your opportunity to up-sell these services and products, and to get as many of your clients as possible to spend money in these areas again.
It does not take many clients, each spending say £10-£15 each more to start building your revenue.