Well this isn't out of any books but common sense tells me that as a pilot with my butt on the line (along with all the people in my care) if I was given a requirement to be FL310 X Timbuktu and then subsequently was cleared to FL350 whilst I was passing FL210 I would EITHER ask the controller if the previous requirement still applies, or meet the requirement anyway as you can never be too careful.
On technique as a controller if I ever change a clearance in any way and there is an outstanding requirement linked to that clearance I will reiterate or cancel the requirement as part of the issuing of the new clearance eg. "ABC climb FL350, still requirement reach FL310 by Timbuktu", clear and no confusion.