Just get her to read the passages in Matthew 24 and 25 that talk about Jesus returning in glory and power and sitting on a glorious throne and ask her why the Society believe Jesus became King in 1914 when the official current Watchtower interpretation of these Bible passages is that they are FUTURE events!
Ask her what exactly Jesus has been ruling over since 1914 as there is no physical evidence of his reign. Is he ruling over the angels only? Is he ruling over the Watchtower Society and all Jehovah's Witnesses only? Is that what Jesus rule and the Kingdom of God means?
Ask her how could Jesus could have returned in Kingdom power in 1914 yet the 1,000 year reign hasn't started yet? Wouldn't it make more sense that Jesus' return starts in the future, when the great tribulation starts?
Ask her who the ruler of this sytem of things is. When she answers "Satan the Devil", tell her that Jesus must be sharing his rulership with Satan since 1914? Does that make any sense? Since Daniel 2:44 says that God's Kingdom will crush and put to an end all other Kingdoms, ask her how on earth it is possible that the Kingdom has been reigning since 1914 but all the other kingdsoms and rulerships of the world have carried on exactly as they always have...is Jesus sharing his rulership with the earth's human rulerships?
Tell her that there are too many contradictions and question marks over the whole 1914 thing and you do not believe the "short period of time" in Revelation 12 is 96 years and counting and that you believe the bible makes a whole lot more sense when we put Jesus return, the ride of the four horseman, the "sign" of christ's Presence in the FUTURE, not as events that began to be fulfilled 96 years ago.
good luck
yadda