Avoding repeated queries while working in a WSN set-up of Coordinator-->Repeater-->End Device , when Coordinator and End device are in Range
The standard approach, used by ZigBee and other multi-hop mesh networks, is to include a sequence number in each packet.  Each receiver keeps a history of sequence numbers that it has received and uses that to ignore duplicates.

There's a much longer discussion to be had on how many bits long the sequence number needs to be, and how many items you keep in your history buffer, but that's highly dependent on other factors.

You may wish to review the IEEE 802.15.4 documents to see how one system handles it.