First of all lets be clear on all the statuses here.
Am I correct that:
You are employed by a company. Company X.
Company X has a big contract with somebody else (4 years) call them Company Y.
You did the work to get that contract into place, hence you call it "your contract" (although the contract is between company X and Y - not you).
The 4 years is up, and that contract will be renewed, or not - maybe given to another company.
you are asking if you should drop everything and make sure that contract gets renewed, even though it may not be your job?
It seems to me you should ask your boss what they want you to do with your time. That's their job, to have you do what is best for their company.
