Tough situation, mt heart tells me go the whole, but my head tells me half to judge. I have never been in the situation where i have had such an extended break but knowing me i would take the whole, seeing as i have had breaks of 3 - 6 months and done so. So i guess that my thought process would be same.
If you want to be really safe though, don't take any. Who knows how much is in the next pill you take.