Because our feet are contsantly changing and orthotics used in sport get quite a battering, it is wise to get your orthotics checked out and possibly replaced every 12-24 months. Whether yours can be repaired or not would need to be answered by a Podiatrist, but you defintiely need a check to see if your feet have changed and you need a complete new pair.
You can get free Orthotics through some NHS depts. If you live in birmingham, ask for a referral to the Hall Green medical centre podiatrists, which I have used to get free orthotics.
It might also be worth getting some technical running advice to make your running style as efficient and low-impact as possible. This will help your joints as well as your orthotics last as long as possible! I can provide this service if you're interested: http://www.athomefitness.co.uk/locations/personal_trainer_birmingham.html