Losing BT speaker while using keynote

[glen e]

I use a ipad2 for keynote presentations, paired to a logitech z515 BT speaker. It works very well, but sometimes if I wait too long before using it, like 10 min or so, I lose the BT connection and sound reverts to small HDMI speaker in my Epson projector. Re-pairing while people wait is cumbersome.

Reason?
Anything I can do?
Maybe place speaker on one side of iPad? ( it sits within 2 feet of pad when using, not across room)
Forget other BT devices?

Thanks in advance