Like RevdKathy says, very likely you just need to free up more space on your rootfs. The link given by Rob1n is very useful, but details a lot of stuff you probably don't need to worry about.
A quick 'n simple explanaton on making space and installing PR1.1 OTA:

1. Uninstall any software you installed from the extras-devel repository. Uninstalling stuff installed from extras-testing may also help.
2. Disable the extras-devel repository in App Manager (and possibly extras-testing).
3. Reboot.
4. Check to see if you have at least 48-50mb free in your rootfs. Open a terminal, type 'df -h' (no quotes).
5. If you have enough space, good - go to Step 6. If not, you probably need to uninstall something else.
6. Make sure your battery is fully charged.
7. Open the App Manager, tap on 'Update'. Simple from there on, just be patient and let things finish.
8. Enjoy!