I did not upgrade Lion Developers Preview build 11A390 to OS X 10.7.2 at all. What I did was I figured out how to install the Server App and Server folder (both in the Lion 10.7.2 Server's Applications folder) from Lion 10.7.2 Server and the Server Essentials package from Lion 11A511 Server into Lion Developers Preview build 11A390 to enable Lion Server in Lion Developers Preview Build 11A390!
This made Lion Developers Preview Build 11A390 into Lion Developers Preview Build 11A390 Server!
Here is how:
1) First you copy the Server Application as well as the Server folder from Lion 10.7.2 Server into the Applications folder in Lion Developers Preview Build 11A390.
2) Then copy these folders from Lion 10.7.2 Server into the same location in Lion Developers Preview Build 11A390: ServerAssistant.framework, ServerFoundation.framework, ServerKit.framework overwriting any previously existing copies there.
3) Repair Permissions with Disk Utility, (very important).
4) Install the ServerEssentials.pkg for Lion GM 11A511.  This is the most difficult part as its tough to find this package!
5) Use Property List Editor to edit the ServerVersion.plist located in: Library/System/CoreServices, by changing the ProductBuildVersion from 11A511 to 11A390, otherwise when you go to "About this Mac" it will show you that you have Lion GM Build 11A511 installed which you don't.
Presto, now you have a 100% working  Lion Developers Preview Build 11A390 Server!