Yes, retake the ielts and submit with the application . I have gone through the same problem, my ielts expired three weeks before I got the nomination.
You have to score similar or higher score than the one you submitted.
Nobody will give you an answer for not to retake the test. Even I communicated CIC and SINP both did not advise me to take or not. So I have chosen to retake and scored the same band 6. Although they indicated the ielts must be submitted for NOC , b and C and nothing mentioned about NOC A. However, I decided to delay my paper submission and submit it with the ielts score.
My NOC 2132
OID August 2017
Nominated November 2018.
Application received on 4th January 2019
Waiting AOR
Good luck