If you’ve gone through a hard time and your GPA is suffering a little bit, definitely focus your energy on that before committing to long hours in the lab. Your GPA and MCAT scores are the non-arguable parts of your application; make sure these are as impeccable as possible, and as soon as there’s an improvement, move on to research.
That doesn’t mean that you should completely forget about the “extras” of your application; as long as you keep a balance between a good GPA, scores, work, and extracurriculars, you’ll be on the right path to creating a competitive application.