Agreed with above. You really need to know your rates before you agree. Hopefully you told them, "I will call to confirm my rate within the next two days" etc...
As it is a corporate event, they will most likely be willing to pay as much as you would like, provided your sales pitch of yourself warrants as much. If you ask for 300$ and hour, but are stumbling with your words, aren't clean shaven, use words like, "umm, I don't know, I guess like, uh... 300$ per hour maybe?" you will get shot down immediately. Go in there with a strong confident attitude and say, "My usual rate for corporate events of this size and venue, and under these conditions is a flat rate of 300$ per hour, and an addition fee for a short stage performance if desired. If you would like to further negotiate this figure, that is very possible, but perhaps if you could show me an itinerary or time schedule for the event so that I can see more accurately how much strolling performance time there will actually be." bla bla bla.
Another thing... like the above poster mentioned, keep your hard-hitting (reset required etc...) tricks for the VIPs/ Board members etc... and let the organizer know you you would like to get them together for a special show. Other than that, 5 routines is more than enough, as long as you don't need any downtime for resetting. For example, if you are doing Chicago Opener (red hot mama) to open one set, don't open with it in your next set.
Lastly, research a lot about the company before the event so that you can throw details of the company and its projects/ business dealings into your routine/ patter/ or small talk with the guests. If you can look educated in their territory of information, it can go a long way into being hired again.
edit: Some additional info on hard-hitting effects you can do. Get the names of the board members from your research, or if some of the board members bring their wives/ children, try and obtain their names from someone else. Write their names and a "thank you" note on a jumbo card. Do a force routine of that card for the person, and at the end say, "Hi, your name was XXXX right? I believe we are meeting for the first time. Anyway, I have a small present for you..." and present the jumbo card with their name on it.
Also, Fusilade (multiple selection routine) by Paul Cummings can absolutely floor a group of 5-15 people.
