Villagers don't seem to reset / replenish their trades if they were locked before the update. I spoted that in my survival world on BDS, where I had a villager - he has locked one of his trades in previous version, so I tried with more trading after update to 1.8. After spending 30 emeralds, (3 per trade, so 10 trades), he hasn't just kept that trade locked, he also locked another (this) one. Trading, once again. And I gave up when he locked his 3rd trade. No replenishments at all ... Doesn't affect new villagers though.