Hi! I was in a similar position this time last year (gearing up to begin a second round of applications). I used the extra time to 1) gain further language skills that would help in my research; 2) apply to outside funding--writing the grant proposals ultimately helped me tighten my SoP a lot; and 3) really, really, really brush up my SoP--making sure to go back through relevant sources, concretely outline my proposed research and supporting experience, my project's theoretical backing, practical utility, etc. It all worked out & I'm heading to my top choice program in the fall!
All that said, I'm more than happy to look over any proposals, talk more about my experiences re-applying, or help in any other way I can!! Good luck :-)