isnt it ur offer letter valid for the next three terms? what are terms of condition of ur offer letter?
if u dont wanna take a risk, take ielts again and apply for a next term
otherwise u r short on time for jan intake if u still wanna have a go at ielts exam
so that cant be possible.
if i were you, i would not submit ielts score since it is not a mandatory requirement...u might get away with it based on your good academic credentials.
you still can submit it.....if u want to take a risk...but 5.5 is too low for my taste. visa officer will def raise eye brows over it...