Although it loses accuracy, you can use dilution to get a ballpark figure when you need to test higher chlorine levels than your kit can normally register.

Take one part pool water and mix it with one part distilled water. Then, fill your tester with some of this mixture and test as usual and multiply your results by 2. If that doesn't go high enough to help, mix one part pool water with 2 parts distilled and then multiply results by 3, etc. You do lose accuracy with each dilution so it is not ideal, but better than nothing. What you need to do is to go ahead and get a good test kit like the Taylor K-2006 so you'll have it.