The eminent Muslim scholar and renowned Da`iyah, Sheikh `Abdel Khaliq Hasan Ash-Shareef, states: It is permissible to repeat the suras you have recited in Fard in sunnah. So, if you have recited surat Al-Kawthar and Al-Ikhlas in Fard, it is permissible to repeat them in sunnah Prayer and there is nothing wrong with that.