I guess a whole system clean. The only thing i can find installed is the Safari internet history and search history clean. I wondered if there was anything that went a bit further than that.
Also, its a ipad2 so its getting on a bit
Go into Settings > iCloud > Manage Storage & delete all the apps you no longer use. Or have a clear out of photos or music. Whatever is taking up the most space. If you have an ipad2 and it has a small memory the memory will be used up from all the updates.