How to update without losing my jailbreak?

Is there anyway I can update my iPhone 5 without losing my Evasi0n jailbreak?

Unfortunately I don't believe there's a way but after you update you can immediately re-jailbreak your device.

FYI I recommend in-jail breaking before updating.

No, updating always results in the loss of jailbreak… But be aware that 6.1.2 is still covered by evasi0n so you are still alright to update and re-jailbreak. Be quick though, as apple are soon going to come through with another update that won't be covered by evasi0n most likely. Please read the following:

Don't follow ANY links that people post here that arn't leading to official iPhone dev team websites. Trust me I keep a close eye on all this sort of news and there are only a few sites that are official. All the others will lead to viruses and malicious software downloads.

The best thing you can do is 'like' the following page on Facebook:
Www.Facebook.com/jailbreak101

These guys always post the correct download links to follow on the day of a new jailbreak release and it ends up as part of your news feed so you're never out the loop.their 'notes' section is very resourceful as well, showing you how to get the best out of your Device once it's Jailbroken.

There's NO way for updating without losing your JAILBREAK.

Nope. You will have to redo the jailbreak.