There's no deal currently, it's a separate purchase. There are several reasons I decided to make Recharged a separate new version, one being I needed to keep the original a small file size. With Recharged I wanted to be able to add as nice and detailed maps as possible without having to worry to much about file size and graphics limitations.
The main difference is that there are some larger and more detailed sceneries in Recharged. Also, there is some extra functions such as flight recording and the ability to move the LOS viewpoint.
It is also quite a bit more demanding graphics wise, so it needs a bit more powerful computer to run smoothly.