Things to clarify
1) Door of tawba is never closed. Whatever you have done or whether you have betrayed your tawba many times there's no need to be desperate. God is always open to tears of a sinner. He says He likes the tears of a sinner most among other things. And He also says that if we (humans) were a nation with no sins, He would create another which will commit sins and then regret. (This is also a proof that He does not intervene in our will).
2) Journey to God, or pleasing Him, is an endless quest. What wonderful person you may be there are always better. To your surprise it is narrated that Prohpet Muhammad pbuh committed tawbah 70 times a day. That means he took 70 steps each day on his journey to God, and made tawbah for his former position. That is he always made tawbah for not being better.
This continous awareness is called taqwa.