No unfortunately there is no way to upgrade your apple device. Apple hand sets are very particular and have no room for upgrades. How ever if you want your phone to be more efficient and fast like it was origianlly when you first got it, before all the pointless updates destroyed its performance, you can down grade the IOS system back to something more early. This may cause some complications with some apps that no longer support certain older IOS softwares, but this will make your phone faster. Due to the newest IOS that apple released recently (which they are getting sued over right now if you have not already heard) it is slowing down the older generation iphones to push you to go buy the newest one. But you can download a software called 3utools at
http://www.3u.com/
Definitely be careful using this software, ifixit.com and myself are not responsible for any damage you may cause to your phone in the process. It is not advised to download 3rd party softwares to tamper with your phones firmware.
I hope this helped in some way. I wish the best of luck to you. Let me know if you have any other questions, thanks.