Should one repeat the supplication if a worshiper forgets to invoke blessings upon the Prophet (peace be upon him) during it?

Among the etiquettes of supplication (du'a) is to begin by mentioning Allah and sending blessings upon His Prophet. However, this does not mean that a supplication is invalid without it. So, if someone forgets to send blessings upon the Prophet (peace be upon him) in their supplication, their supplication is valid, and they are not required to repeat it. If they were to repeat it after praising Allah and sending blessings upon His Messenger, that would be better.