Reducing English listening ability

Recently I am feeling my listening ability is reducing.

I have not been listening English with concentration. So even when I concentrate to English, I couldn't listen decently. It's a terrible situation for me before Eiken test.

Of cource I'm continuing studying NHK English cource, but I had more hard, longtime training before. My training time was almost 4 hours before.

I don't have a special will for English abilities lately, so I don't need afraid to reduce my English ability a little.