Shall I apply again after all my PhD applications are rejected?
Age is not a discrimination in your age range, there will be opportunities when you complete your PhD but you should ask yourself what kind of opportunities are you seeking by completing a PhD.

If you stay at the same job your LOR will likely be the same in one year, so you have to change something else. I would suggest you reach out to 1-2 professors whose work is closely related to your job and see if you can be involved in one of their projects, and see if this can also benefit your company. I am afraid if you don't build a more direct connection with academia/research your chances will stay low. Otherwise you have to aim lower, less prestigious schools, but then we go back at WHY you want to do a PhD.