If you have the 70 point BCV contract for the 11 month window there, and you still want to stay there during difficult to secure seasons at BCV, then I'd keep them that way. If you think you are likely to rather stay at AKV, then I would definitely sell and buy at AKV.
We did a similar evaluation thinking that maybe we should sell one of our OKW contracts and buy the same size one at AKV. The problem is that it would cost significantly more at AKV than we would get from the OKW resale (should it even sell), so we decided to add on a smaller amount at AKV instead. We can still use our OKW points at AKV at the 7 month window, and by purchasing a smaller add-on, we wont be making a huge addition to our maintenance fees. The only thing that made me pause about this decision is that the AKV ending date being 50 years from now means we could sell after 20 years, and still see a significant amount back on it. In 20 years, our OKW contracts will definitely be worth significantly less with only 15 years left on the contract. I'm still thinking we may consider doing this at some point in the future.