Go back and re-do just the games from the tests you've already done... after you've finished one, review it, not just look over it, review it, pretend you're writing out explanations for the game/deductions/questions a la the LGB explanations, when you really really really understand that game, move on to the next game and do the same thing....
Don't just keep taking tests, if you haven't seen any improvement so far, you need to work on the fundamentals before plowing through any more... it's likely you could just work through all of your tests without really learning anything...