Have you tried friends reunited? If she is on there, you can send her an e mail.
Other options are facebook or bebo search.
Alternatively try googling her name and kenya.
Did she pay to have her mail forwarded, you could send a letter to her old address, or even ask the new owners if they have a forwarding address.
What about her old workmates - will any of them have a contact for her.
Mobile phone number -has she left a voicemail with new contact details?
failing all of these, your only other alternative is a nice long vacation trip to Kenya......