Yesterday I mentioned I was basically doing less rolling and more decisions about what monsters go where when I restock. And putting in less in general.
And I linked in the comments to how I do it - wandering monster rolls and Reaction Rolls.
What if you like the idea of rolling, and want to keep rolling, but want less restocking to occur?
You have three broad options.
Less Frequency - instead of making restocking rolls between every delve, make it between every X delves. Or, if you're running a one real world day = one game day game like I do, space it out from bi-weekly or monthly to bi-monthly or once a quarter.
Lower Rolls - roll as usual, but move everything down a peg. Wandering Monster rolls that would re-stock on a 9 or less become a 6 or less. A 12 or less becomes a 9 or less. 6 or less becomes 3-4 only.
For Reaction Rolls, require a higher margin of success. Instead of Good, require Excellent.
You can also do this with modifiers to the Roll - instead of using a lower roll, roll as normal but give a flat -3 to either case to move it down just as far.
Roll for less places - instead of checking each keyed area, or each group, check a fraction of that. Perhaps one-half (1/2) of all cleared rooms. Roll for every other group (or simply give them half of what seems like an appropriate reinforcement level.)
Personally, I like all three of these but would favor "Less Frequency." Still, not rolling is a little easier, which is why I'm doing that right now.