How to update Jailbroken iPhone 4?

Okay so I want to update my iPhone 4 running iOS 7.0.6(Jailbroken) to the new iOS 7.1.0. I want to do this because it's a Opportunity to loose the jailbreak. But here's the problem I used evasion to jailbreak and I just found out it blocks out software updates. Is there any tweaks or ways around this? Oh yeah I don't have a computer either so I can't restore.

Without an iTunes backup on a computer, I think you will have to take it to the Apple store. Tell them it was Jailbroken, and you want it wiped clean with the upgrade.

Since you have no computer backup, you will lose anything on there that was not backed up to the cloud. It will be like a brand new phone. Any iTunes purchases you can re-download without having to pay for them again.

Determine what version of iOS you are running. To do this open the Settings app on your Home screen. Tap the General category and then select About. Your iOS version # will be listed next to the Version entry.
JailbreakMe DOES NOT support iOS versions above 4.3.3. This means that the iPhone 4S, 5, iPod touch 5, and the iPad 3 are all not supported. Older hardware must be running iOS 4.3.3 or earlier.
If you'd like to jailbreak a newer iOS device, check out our guide for iOS 5.X and 6.X.
Backup your device. Open iTunes on your computer. You will be using iTunes to create a backup image of your phone. You can use this image to restore your device in case the process goes wrong, or you are unhappy with the jailbroken device.
Plug your device into the computer. In iTunes, click on your device in the sidebar. Choose "Back Up Now" from the options that appear. This will backup your data, contacts, and settings.
Turn off the passcode screen lock if you have it enabled. You can re-enable it after the jailbreak process is over.