As I understand it, you only replenish Edge up to your rank as per the following:
Characters start a gaming session with Edge points equal to their Edge rank.
The book states that the only way to gain edge you have to earn it, and that:
In the session,
Edge can be carried over and accumulated up to a limit of 7, including the Edge provided by the character’s Edge attribute. Any Edge garnered over your base attribute goes away when you complete any ongoing confrontation; this includes combat, hacking, social persuasion, and any situation where bonus Edge might be accumulated. If, at the end of the confrontation, your current Edge points are less than your Edge attribute, you stay at the lower level.
So if I'm hacking a bunch of devices as legwork, at the end of the hacking "confrontation" excess Edge beyond my rank is lost, but Edge up to my base attribute remains". There is no rule against using said edge in Combat, so penllawen's example is perfectly valid.
Even going into VR for a turn or two during combat to interrupt your foes (Spoof Command with Fork works wonders here) will likely boost your edge (see above on AR vs DR and Analytical Mind), to the point where when you leave VR but are still in combat you would retain all edge gained up to a max of 7, and would be free to use it for Anticipation as normal, for example.
This isn't exploiting the Edge mechanic; this is using the Hacker's abilities to directly influence combat through the Matrix, and the side effect is a pretty aggressive rate of Edge gain that is RAW. No interpretation needed.
The core of this issue, to my mind, is how exceedingly easy it is for deckers to earn Edge when fighting devices that are not protected by a dedicated, specialized decker or host. The GMs only real option is to throw in an NPC decker to protect the NPC gear, which again, we don't really know if should be common or not because the Matrix chapter doesn't really tell us. We have good examples of magical and physical security by security zone, but not a lot to go on as far as Matrix security.
Definitely one for a Matrix supplement to elaborate on; it once again comes down to individual interpretation of how the Matrix functions at a core, system/world level.