Here are some of my tips:
1. If you are bold and feel like it is not an issue, then just remind them like it is no big deal! You can stop in on their lunch hour, at the end of the day, or during a study lab to talk to them about it. Just be honest with them and remind them of the deadline. They may have a plan to complete it soon, but just haven't because they've been so busy.
2. You can "thank them in advance," as a way to remind your teachers to complete their evaluations and letters. Teachers are busy and may have a lot of letters to write, so a soft reminder like this will make them grateful. They honestly may have forgotten or lost track of time, so a "Hi, Mrs. Jones. I just wanted to thank you for writing my letter of recommendation and doing my evaluation, please let me know if you need anything else from me to complete it."
3. If you don't want to confront them face to face, then send them a professional e-mail with a reminder of the deadlines for each college they are evaluating you for. Much like above, reiterate how thankful you are for them writing your evaluations and helping you towards your dream of attending college. You can also say how they have helped you choose the institution or program you are going to pursue and why they are important to your schooling career.
4. If you've reminded your recommenders already and they still haven't completed your evaluation then I would enlist in the help of your guidance counselor to reach out to your teacher and reiterate the importance of their timely completion of the letter of recommendation and evaluation. Your guidance counselor may also be able to contact the Admissions Office of the universities to which you're applying about the delay in the recommendation.
Ultimately, do whatever feels naturally to you and your personality when you are reminding your teachers to complete the evaluations and if you think you need to change your recommenders, then do what is right for you and your college applications. I would definitely talk it over with your parents and your guidance counselor before you ultimately choose to change who your recommenders are.
If you are facing this issue, I hope this post has helped you determine your plan of navigation for reminding your teacher. If you have other questions or concerns along this line, please let me know and I would be happy to do a post about them and give you my recommendations!
enjoy the chase,