On Windows, uninstalling DB2 will remove the instance but keep the databases in place. After you reinstall, you’ll want to recatalog these databases. This is fairly straightforward.
Find out their names:
db2 list db directory on C:
Map each of the databases that you want:
db2 catalog db SAMPLE on C:
You can also catalog remote databases the same way. In my experience, this is much easier than going through Control Center:
db2 catalog tcpip node MYNODE remote MYHOSTNAME server 50000 db2 catalog db SAMPLE as MYSAMPLE at node MYNODE db2 connect to MYSAMPLE user MYUSER using MYPASSWORD
The database will now show up in your Control Center catalog. You will also be able to connect to the local alias from Data Studio and other tools.
Reference
Leo on Tech 