The only reason anyone said it needed to be plugged in had to do with the fact that anyone who tried it unplugged (not charging) couldn't get it to reset. Maybe an extended amount of time in airplane mode would do it.
Someone in a previous post mentioned they use Juicedefender to extend battery life. I downloaded and tried it on 2.1 It's got a slick interface that lets you read the app's activity. But it kept saying "ERROR: No APN found!" during it's routine network disabling process. I wonder if that has anything to do with the cell connection issues. I find that it really doesn't do much on my phone.
Edit: BTW--just tried Airplane mode w/o plugging in and it worked to correct "Time without Signal" stuck at 50% issue. It's been steadily going down while the phone sleeps since coming out of Airplane mode. I had it in Airplane mode for about a minute.
Also, on the FAQ for this app, the dev. mentions this issue:
"
The mobile data (APN) connection is not restored
It might happen (quite rarely) that the mobile data connection isn't restored, say after turning the screen on. This is not caused by JuiceDefender
per se, as you can verify from the log (the APN gets correctly enabled) and in your APN list.
The problem is caused by the fact that the
GSM cell refuses to reactivate the APN connection. I have very little data about this, but I think it's cell-specific and probably depends on how much that cell is under heavy data usage load.
Usually when this happens, putting the phone on Airplane mode and back is a quick way to get the connection back, as your phone will have to reconnect to the GSM stack of the cell, and the cell just cannot refuse that - this is often enough to also get the APN connection back."
Sound familiar? I know our Verizon is not GSM, but it may be a similar issue.