moving DHCP from one server to another

here's the problem, I'm having some dhcp server problems, so I didn't want to export the databases, I wanted to create it from scratch, so I don't import the dhcp problem over to my new server.  But perhaps since the data is just a .txt file, the new server might not experience the problem.  I have PCs not able to get IPs from my dhcp server and then I have "bad_address" listed numerous times in my dhcp server.

Can I perform this transfer during business hours? I'm assuming the PCs that have the lease, should continue to be fine until the lease expires, right?

so with DNS, I will create two new DNS servers, but how do I replicate the data from the old server to the new server, I'm not sure how to do that, and now sure how to decommission it?

Also, I'm still planning to use that server for a few more months, as I have other crtical programs running on it.

Clients with a lease will try to renew that lease periodicallly.  It won't hurt them if DHCP is down, but if a lease actually expires while DHCP is down, that client will lose network access.

What you can do is set and configure up the DCHP service, but leave the service turned off.  Then, after hours, kill one DHCP server and bring the other online.

As to DNS, setting up the additional servers is a snap.  If they're all AD integrated, they'll all end up with the same data once they replicate with each other.  Once the two new DNS servers are set, you can kill the service on the old server.
http://technet.microsoft.com/en-us/library/cc725925.aspx
http://technet.microsoft.com/en-us/network/bb629410.aspx