You are sinful for saying this and must not say or think this again as it can lead to a dangerous road to kufr. Try your level best to fight these thoughts as these are waswas from the shaytaan.
As your your ablutions you do not have to renew it all the time, unless you break your wudu. When praying take your time and try your hardest to stay cam and relaxed. Remember, that when you perform your salah you are in direct communication with Allah, so do not lose hope and stay focused. make lots of du’a and ask Allah for whatever you want.
May Allah grant you Shifa’