Argon Performance on long term use (Battery Powered)

I have developed an application using argon with below specifications to scan the BLE advertisement. It functions as per the step

  1. Connects to internet and sync time from local time server ( time sync happens once every hour after initial sync)
  2. Power off Wi-Fi module after time sync
  3. Started scanning BLE advertisements near to it
  4. Parses the advertisements and save it in internal flash memory as file
  5. Every one min it reads that file, power on Wi-Fi and pushes to server using MQTT and clears file and power off Wi-Fi module.
  6. Same process it repeated

It was working good at initial days and scanned and posted 10K+ advertisements per day but after 2 weeks of usage now it sends only 1K+ advertisements every day. Could you suggest what might be the cause ?

Note*
Argon is powered using 3.7v, 1000mAh Lithium Battery