Ensure she is well versed in the type of test she is sitting by doing lots of practice and take the 5C as encouragement that she may pass if she is well-prepared.
I don't believe there is a strong correlation between national curriculum levels and how children do in 11 plus tests
Bear in mind that a lot of questions in the test may not have been covered yet at school, which is why, if you are tutoring your child you need to be as familiar as you can with the types of questions that she may face.
I don't believe that SATS results have any bearing as to an indication of whether or not a child will pass the 11+, as the SATS are based on what is learnt in the curriculumn, and the 11+ is different. There are many children who pass the test and go into a grammar school with only one level 5 achieved at the end of year 6.
The CATS tests at the end of year 5 are (according to our school) a better indicator as to whether or not the child is likely to pass, and even then it isn't always accurate.