Typically if a MIL-STD (Military Standard) is called out on a drawing, and later it is cancelled, you are not necessarily required to go back and change the standard or spec to the latest or superseding standard/spec. The reason being is that usually when a MIL-STD is canceled, there is a superseding standard or spec listed on the cancelled MIL-STD, so it is typically understood that the superseding standard or spec is used. If there is no superseding spec, you would still need to apply the requirements of the MIL-STD, since this is a contract requirement.
You need to be careful, as in some instances you might have old contracts that still call out MIL-STD-100, for example; you technically can't go in and change it to read ASME Y14.100-2004 until the contract is changed by the controlling contract administrator to show this. Generally, there is no technical problem if you would change MIL-STD-100 to ASME Y14.100 - with the exception of Specification Control Drawings. Specification Control Drawings are now no longer used, and are now referred to as Vendor Item Control Drawings. It probably would not matter to most of your customers, since Vendor Item Control Drawings are commonly used today, but it could be stated in an audit that you didn’t follow the contract stated standards exactly.