Just keep it to the core rules, spell per day. All will be well.
-Doom
The point is that core rules state that Warlocks replenish spell slots on short rest, not "per day." And as others have stated, there are other class specific abilities that are balanced around the short rest mechanic.
SorcererVictor offered the best solution imo. Let the party short rest a limited amount of times between long rests. This seems like an elegant solution to me. There could be a risk for random encounters during short rests to make it a bit riskier.
