How do I stop Grindr Xtra from going online?

Hi,Basically there are times when I like to leave Grindr Xtra on on my iPad at home rather than on my iPhone 5 which follows me about.But it keeps going online on my phone (i.e. I receive message notifications on it) even if I kill the app manually and disable location services for it on my iPhone (set to "never" use my location).I don't want to delete the app (although this does work) because I will lose my chats on there.So how can I disable it on my iPhone?Many thanks in advance