All bitcoins, shared in every day, we get from current site commercial. The number of commercial views and clicks is different, so we got a different profit every day. If profit is bad, the number of bitcoins will be reduced, as well as reward. We won't stop to share bitcoins, but reward can't be the same every day.
Also commercial network pays in US dollars or Euros. So number of bitcoins is depend of Bitcoin currency rate. That means when it becomes expensive, we'll reduce a faucet reward, but when it's cheaper a reward will grow.
Also a reward is might be changed because of site timer. The bigger timer, the better reward. And vice versa, the smaller timer gives you less reward.
Also sometimes we arrange events, when faucet becomes bigger. These events are published in "News". So if reward became smaller without any reason, make sure it's not a result of event end.