So what are some current methodologies or even automated test software that I could use to refactor current code to be more test-driven?
It really doesn't work that way.
Test-Driven really means that the tests come before the code. So if you already have the code, it's too late to test-drive it. What you can do, on a project which did not initially use TDD, is to start using it. So before you write any new code, you write the test first. Gradually that will add coverage to your existing code base; it will probably encourage you to refactor some of your old code, too, as you discover just how hard it is to write tests for it.