Your current bike has got you into cycling and for that use it has been ideal. But $700 will not buy you a much better bike. Might be a different colour- but weight of the new one and components fitted to it will not be much better.

Upgrading your current bike's components wouldn't help either as all you will still have is an old bike that doesn't work any better.

BUT-- one thing that could probably improve your current steed is a better quality wheel set. Not talking off the shelf- cost an arm or a leg- or a cheaper set that would not be an improvement over what you currently have. I am talking a hand built set of Ultegra hubs fitted to Mavic Open Pro or CXP33 rims. There are plenty of quality builders around that could do you a set of these wheels for around $200. Still a lot of money- but there is a difference. These wheels will improve your bike- and on top of that can be transferred to your new bike when you get it.