How to make Naver line app backup

I need to make the Naver line app backup and same for chat history in Viber. I know one way is to install the Titanium backup, however, I have no rooted Galaxy S2 and I don’t want it because I wish to have my phone on warranty and it can be just when no clearing the Rom or anything done. I have heartd there is the possibility to backup whatsapp, but how about the rest? Moreover, I have saved everything in the phone’s memory. If I will reinstall, it will get back? I can’t understand what to do, help me!
