She would lose her magic, actually, upon ending the contract. 

She would gain magic again with the new contract, and it might be the same magic or something entirely different, depending on the vows made at the time. If it is something similar to the first time, it might end up in the same thing. 

If you are planning on making a dragon [i]dragon[/i] then she naturally has fire breath and extremely hard scales, no magic needed. A draconoid can also use fire and the areas covered in scales are too hard to break through. Ryuu-jin's are more martial arts oriented, tho