Well, the only thing open to you, I believe, is if you didn't actualy max out the number of licenses. For example, you get 6 titles, 50 licenses (unless its a server title). So, if you only picked up 30 MS Office licenses, you could order the remaining 20. If you used up all 6 titles, you can't buy another title, just licenses in the titles you already have.
Good news:
If you purchased Windows Vista Business, you'll get access to Windows 7 since all TechSoup licenses are donated with Software Assurance for 2 years.
If you didn't, you still qualify for regular charity upgrade pricing at about $50 ish per seat.