As for whether she should reapply or not, it really depends on the reason(s) she didn't get into a US school this time around.
Are her numbers good? (GPA + GRE). GRE is generally easier to fix than GPA. If she has a low GPA, she should look at getting residency in a state that has a GPA forgiveness option. If she has a low GRE, she should study and retake (and possibly do better on the new format, anyway).
Does she have a breadth and depth of experience? Schools like to see large animal (particularly, food animal) experience, so if she is lacking there, it would be a good idea to round out her application. She should try to get a variety of experiences but also have a good amount of experience in the area that interests her. This is also a relatively easy category to fix.
Other than that, it's a numbers game beyond personal statement and LORs.
What state is she a resident of? That has a huge deal to do with acceptance to vet school, and if she is an OOS resident at every school she applied to, she needs to apply to more schools and be smart about where she applies to. Some schools take very few OOS residents (GA) and some take more (Penn, Tufts, Kansas, for example), so she needs to apply to schools that she has the best chance of getting acceptance to. If she is not a resident of a state with a vet school (or a contract seat with a vet school), then she may consider moving to another state. If she had an IS school this time around and she wants to give it another go, apply to some OOS schools as well that she is competitive for. Some people get into OOS schools but not into their IS schools.
HTH.