IS there a reason to take another test in general? Or a compelling reason to take the Explore in particular? Would it be useful for the future to actually be able to compare her results on the same test 2 years apart and track growth? She's not likely to take any of the other tests again, so if it's useful to take the same test several times, then I suppose the Explore would be the way to go...
If you're in a school situation where you're going to need a big negotiation in the near future-- like a subject acceleration to more than one grade ahead-- out-of-level testing results can be useful. If you're not in need of that leverage right now, I'd see little reason to do it.
You already have so much testing. I'm against "just in case" testing as a general thing. We test when we need information.
For kids at higher LOG, there may be no value in a retake because they may max out the test the first time. DS12 maxed out Explore when he was in 4th grade-- there was no reason to do it after that because it would not have yielded any information. He then took the ACT in 6th, because we needed it for advocacy. It's important to gauge the level of the out-of-level test, and what level you think your child is working at, and what information you bet the test will yield.
The most useful thing about Explore IME is that it includes science. It's possible to get math and reading levels so many other ways, including the testing she's already had.
Personally, I wouldn't do it unless you envision a concrete use for the result.
