Are you on 7.7.01 or on 7.6? If on 7.6, you can not, but if on 7.7 yes you can.
I just went from 7.7.01 to 7.7.03.
Here were the steps that I took
Client install on Linux using Weblogic 10.3
1. Stopped/Un-Deployed the war files
2. export PATH=$PATH :/opt/beatest/jdk1.6.0_24/bin
3. Copy the install file to the tmp directory
4. Created a backup of the IBI directory
5. chmod 755 wfclient.tar
6. umask 022
7. tar -xvf wfclient.tar install
8. ./install
9. Upgrade, not full install Option 2
10. Renamed the webfocus.war file to ibi_apps.war
11. Redeployed and start the instance
Reporting Server on Windows
1. Just ran the .EXE and did an install on top of the 7.7.01 instance
Report Caster
1. Ran the .EXE on Windows on top of current version.
WebFOCUS 8.1.05