7 actually...
But if the ride is constantly buggered, and the company who original made it are no longer producing parts for it, the park MUST consider the benefits against the high costs of maintenance and the unreliability the ride has had over the 7 years it has been open...
No ride has a specific lifetime, but if Slammer keeps playing up like it has been, then it's time might be coming to an end...
Imagine the potential if Thorpe removed Slammer, NWO, the Arena and Storm Surge eh?