Can be an issue of uncalibrated battery.
Try this:
> Charge phone to 100%
-> Restart phone [to be sure it isn't off by some amount (if phone off just unplug AC adapter for 30 secs and plug back in)]
-> Wait 20 min after you are sure it is 100% (phone should stay plugged in)
-> Boot in to recovery
-> wipe battery stats (advanced)
-> Get ready to pull battery and unplug phone and do so after the screen goes black after tapping restart device (pull AC adaptor first)
-> Wait 30 seconds and replace battery
-> Allow phone to boot
-> run through ENTIRE CHARGE (COMPLETELY DISCHARGE) the battery (whether normal usage or looped media files whatever you have time for)
-> restart phone to be sure it is totally dead
-> Charge fully one more time
Source: Link
Hi Connie, have you checked if the battery is still able to hold a charge? It might be because the battery is getting drained to the point that you need to recharge to use the tablet again.