Either of the two courses of action described in this inquiry appear to be viable. If the requiring activity still needs the items, then reestablish an appropriate delivery date via a bilateral agreement with some consideraftion (e.g., a small reduction in price of this delivery order or something else of value). Or second, terminate this contract delivery order for default and follow the appropriate procedures in the contract clauses and other guidance in the FAR, DFARS and your agency FAR supplement. We can see no other viable options for resolving this situation given the facts presented.