Continue to use your existing allocations for self-signed application usage on Symbian OS v9 (that is, those applications not requiring access to sensitive APIs). To do this, simply replace the first hex digit (a 1) with F, and leave the remaining digits unaltered. This maps your UID into the Legacy UID compatibility range, where it will not conflict with any other allocations. For example, you have a UID allocation 0x100F55BE that you can transpose to 0xF00F55BE for use in an unsigned Symbian OS v9 application.
If your application is to be Symbian Signed, you need to reapply for your UID at the Symbian Signed Web site.