Hi @Anonymous User
Two to three months useage out of a NowTV smart voice remote controller is pretty good, where i am lucky to get a month before swapping new batteries.
The reason why the NowTV smart remote eats through batteries is that the remote is constantly powered on over the wifi network (unlike a standard infra red remote), which is the direction NowTV / Roku went with these particular remotes.
With the loss of signal between the remote and Stick, you could try a different wifi channel on your Router or if your Router is dual band try both 2.4ghz and 5 ghz wifi frequencies with the Stick.
If you have a HDMI fly lead extender, you could try that to see if there is any improvement (though i can't guarantee it will help much with loss of pairing with the NowTV smart remote).