Refreshing the 4th Charge is counted as generating a Charge, there's just nothing to further increase numerically. Or, to be more precise, Blast and Missiles always generate a Charge, as do some of the new spells like Charged Up, no matter the Charge mechanic's limit of maxing at 4. The only thing that doesn't "generate" a Charge is Explosion's charge refresh mechanic, unless of course you manage to get lucky and cast it that one time out of fifty when it actually does generate one. I feel like I could have explained this way better, but you get it.