Decided to try out (experiment) this migratory cover as is with a nuc.
Went through at least month of on and off rain showers with no problems.
Would you Replace, repair or leave as is?
(http://lh5.ggpht.com/_EVyVg8TEhrU/TDI0_v-oy4I/AAAAAAAAAso/KKT9j6Q8v-4/s400/review-1%20056.jpg)
Since you are in California and we probably will not get any rain until next October/November, it doesn't really matter if the top is old or new.
The bees don't care. They have probably sealed all the cracks with propolis and made it water tight. Unless the appearance is bothering you, I'd leave it alone.
As long as it work, the price is right.
I'd paint it with a latex, but that is strictly personal opinion - I honestly couldnt tell you if it would extend the life of it.
I never throw them away unless I can no longer keep them together...