It doesn't make sense to get that re-celled. It'll cost a lot more than a new one. It's a standard water bottle battery that you can get from Ebay or Aliexpress. In fact, you can replace it with a Dolphin battery if you want more capacity or other water bottle types if you want smaller and lighter. You can use any battery of the same voltage you want. It's just two wires to the controller.
If you can't be bothered to take the two screws off to remove the receiver or solder the two wires, there are plenty of direct replacements, but note that there are three types of those water bottle batteries, so make sure you get the right one. There's your type with the round 4 pin connector in the base, the type that lift upwards and have 2 pads on the bottom that contact 2 spring pins in the receiver, and the type that twist out sideways and have 4 slits in the bottom that engage with blades in the receiver.
To use a different downtube battery, you just uncrew the two screws that hold the reciever to the frame. You can can then fit any other type of downtube battery, most of which have a much more convenient release mechanism than yours. Batteries nearly always come with the receiver, but check the listing to make sure. After installing the new receiver, you just have to remove the connector that screwed to your old battery and solder the two wires to the new receiver. Make sure you get them the right way round. The whole changeover takes about 5 minutes. Don't get a Hailong (08) case battery. They're much harder to fit.
