How long should a well maintained chain last and what can I do to prolong its life? I commute on a fixie. I'm using KMC Z410 chains.

Every evening if it's wet I wipe and re-lube my chain, using ProLink lube. Every weekend I remove the chain, soak it in kero, brush it with a citrus degreaser, allow to dry and then re-lube.

My current chain is 2 months old (about 800km) and is over .75 already so I think I'll replace it this weekend. Mind you, it is winter here and it's been pretty wet most weeks. Also there is a lot of fine sandy grit on the paths I tend to ride.

I read questions like this and am amazed how long people's chains will last. I don't mind replacing the chain often as it's a cheap chain ($15) and I want to protect my chainring and cog.

Is there anything I'm doing wrong with my maintenance regime? Is it surprising that my chain isn't lasting that long? Or is everything okay and I should stop worrying about it?

Update: I relaxed my maintenance regime. I just wiped down and re-lubed occasionally. The chain was very quiet and smooth. However today, after just 20 days and 353 kilometers, it's already over .75!!! I checked the chain guage on a new chain and it is definitely indicating that the new chain is under .75. Why am I burning through chains so fast?

Update: A little about me and my riding. I weigh about 88kg (195lbs). I ride fairly aggressively on bike tracks on the way to work (I almost never get passed). There are some hills so I am reasonably often out of the saddle and pushing pretty hard. I will take the old chain into a bike shop next weekend and let you know what they say.
A new chain has factory installed lube inside on the bushings and pins. It is a thicker, stickier lube than anything you can put back on the chain after a cleaning which is that thorough. 

I love that you take time to maintain the bike. Definitely check your chain checker, as Daniel said, but on your next chain, try relaxing the maintenance a bit. 

Clean the chain by spraying a light citrus degreaser on a rag, folding the rag in the palm of your hand, and running the chain through the rag. This will clean the exterior and the accessible bits without soaking away the internal factory lube. 

Once clean, lube the exterior of your chain with a quality lube (I like Boeshield T-9 or Dumonde Tech yellow) and wait 15-20 minutes. Then wipe off all excess lube. 

Starting with your new chain, do that for the first 6 months, or until your fresh lube job sounds unlubed again within a few on the bike hours. 

Once that is not working, go back to your current method. I'd say do the complete strip and relube once a month, with the process described above on the in between weeks. 

After your next chain, let us know if and how your mileage changed.