There is no real guideline to say that a life raft only lasts 10 or 15 year. I can tell you this. Revere has a 12 year waranty on their life rafts and it wouldn't be uncommon to have it in service for twenty years. The importance here is to have it reguarly serviced by an authorized service station. Some years the bill is going to be higher than others due to the work that needs to be completed that will ensure your life raft will work when needed. As a ten year old raft you definitley have many more years left, but let an authorized service station doing your work tell you that.
Life Raft and Survival Equipment