Hi,
At 15% abv you are approaching the limits of this yeast. Pitching yeast into a 15% abc environment is very stressful. Normally the suggested limits for bottle conditioning are 12-14% abv. I don’t have any other yeast recommendations, sorry.
It is possible that it may work, but I could not guarantee results and I would recommend that you modify the procedure a bit as follows:
If you cold crashed your beer, let it warm to room temperature before bottling. Use dextrose since this is most easily metabolized (does not require invertase activity). Add your priming sugar to the beer and then rehydrate your yeast using normal protocols on the package. Take a 30% volume of your primed beer and add it to your rehydrated yeast (i.e. 30ml primed beer added to 100ml rehydrated yeast). Wait for signs of fermentation activity and then add another small volume of beer to the yeast and repeat every 15 minutes (subsequent additions can be a larger volume, i.e. 30ml, 70ml, 150ml, etc). Repeat until you have added at least 4x the initial volume of yeast (i.e. 400ml total beer added to 100ml of rehydrated yeast). This will allow the yeast to adapt slowly to the harsh environment of your beer. Add the rehydrated yeast/beer mix to the remainder of the beer and bottle immediately.
Good luck! If you do attempt this, please let me know how it works out. If you have any questions, let me know.
Cheers,
Eric Abbott, M.Sc.