It may be of interest to explore why she is failing the test. Does she understand the concepts and use the correct processes but has the wrong answers because she makes errors with the facts? Example: in long division, can she follow the correct steps but because she thinks 8 x 7 is 57 she gets the answers wrong? Encouraging accuracy, taking time to recheck, etc. may be helpful. (I’m thinking about a particular student at our school right now.) Or is the problem more of an issue understanding concepts and processes?
I attempt to have students visualize what is happening as much as possible; draw pictures to illustrate story problems (or act out the story problems sometimes), use manipulatives they can handle, etc.
If you know where the gap is, you may have to back up and catch up; especially if she is not understanding some foundational areas that the work is built on.
But if you are not holding her hand while she is doing her daily work and those grades reflect what she can do, it may mean that she needs some test taking strategies as Becky mention above. Maybe the idea of “it’s a test” can be down-played to help avoid test-freeze.