My 5 in 1 has lost connection a few times despite the sensor only being about 60 ft away with fresh batteries. It'll hold full bars for about 2 weeks then drop connection to the sensor and I have to pull batteries/unplug.
Is there anyway to reset just the connection between the 2 units without having to completely wipe all the stored info?
Try switching the A/B/C switch of the console to a different channel, wait a bit (maybe a few minutes), then switch back to the original.
What you want to do is get the console back into "scanning" mode where it's looking for a signal without regard to the update interval (i.e. it keeps monitoring full-time instead of just every 18 seconds). Usually when it is in this mode, the wireless indicator will be flashing (at least on the older LCD models).
I'm not sure how long it takes before it starts the re-scan on its own.