BJ,
There are several focusing techniques regularly used by professional and elite athletes.
Visualization and imagery: Regularly picture in your mind your perfect shot from beginning to end.
Learn to identify and control your arousal level. Too much or too little arousal can through your game off.
Look for process cues to regulate your performance rather than game outcomes. Concentrate on how you feel when you approach, deliver, and follow through.
Mental rehearsal. Regularly rehearse in your mind what you are attempting to do.

What always helps me is the following:

Take deep breaths throughout your games.

Think about what you are doing that moment not what your score is.

When you are on the wood of the lanes your thinking about your game but when your on the tile of the rest of the bowling alley you can think about what ever.

The main thing is to concentrate.

What I do is that when I get up to bowl I don't look at anything I just stay focus and try to bowl a strike.

Even though I doubt it'll work for you. I sing in japanese to myself because:
1. It relaxes me.
2. NO ONE knows what I'm saying.
3. Jrock rocks
4. Then you'll be relaxed and that'll help you concentrate.
That's just my thing.

Jack (above) made some great points. Sometimes not trying to stay focused will allow you to remain focused much better... if that makes sense to you. Sometimes when you try to remain focused you will become to tense and intense. Don't watch the scoring monitor and don't begin adding up what you can score.

Less thinking and more relaxing. I find that positive self talk works well.

Think that its only you and your target and relax,i relax by playing my favorite songs in my head and bowl to them!! Good Luck!!!!!