Looking at your profile, seeing that you bowl 30 games per week and are averaging 150, may I sincerely suggest you find a good local coach? I think you may be practicing the wrong things.
Making most of your 1,2, and 3 pin spares should bring your average up to the 180 mark, at least, especially using a Blue Dot. I'd forego buying any new strike balls, until you get some basics down pat; a new coach or a coach may be the most valuable thing you can do, given the time you have to bowl 30 games a week and the money you have to buy new balls.
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"Just because you can do something does not mean you should do it."
"No good deed goes unpunished."