While reciting Namaz,many times my tounge makes mistakes in reciting unintentionally. Example- If have to recite 'Arrahmaanirraheem' , then sometimes the sound of 'r' does not come out or sometimes such other mistakes also happen. Also, Sometimes I feel a doubt whether I recited the verse or part of namaz correctly or it went wrong. What should I do? Till now I have been breaking my namaaz and then restarting again from beginning and reciting correctly and completing the prayers. What am I supposed to do and how to correct it?

If you make a mistake in recitation then correct yourself but do not abandon the salat to redo all over again.

Since you are one who has frequent doubts in your prayers the ruling would be to ignore the doubts and proceed with the prayers.