What kind of robot is doing this drilling? You mentioned the bits only work for about 2 weeks, how many holes are drilled in 2 weeks? Roughly how long does the robot take to drill each hole?
Unfortunately, if you are plunging and using mist, the coolant is never going to get to the cutting face where it is needed. It will just be spraying onto the chips that are already in the drills flutes. To get the lubricant where it is needed, it needs to either retract or you need through spindle coolant.
When you sharpen them, how is that being done? If they are just sharpened by hand and aren't done well, that will contribute to the drill walking while it cuts.
I have found cast aluminum to be particularly gummy and prone to packing into the drill when I am drilling. With something like extruded 6061, I can usually get to 2 or 3x diameter with the drill before the chips stop escaping before it retracts. With cast, it tends to get stuck almost immediately and gets knocked loose from the drill bit once it goes back in after the retract.
There are some things you could try which might help. I am not sure how practical they will be for your application, but nonetheless:
1. Try to peck drill instead of through drilling. This will let it clear the chips and get some lubricant to the cutting surface.
2. If the robot can do it, try using an end mill to interpolate the circle instead of drill.
3. You could drill a little bit under the diameter needed then switch to a boring head and bore it. It will be straighter, rounder, and you won't need to worry about the drill walking.
4. Make sure you are using the right drill bits. This sounds like an industrial application, so weigh the cost of better gear against the time it takes to drill the holes, sharpen, change out the bits, replace them, etc.
5. Make sure you are using a proper lubricant for the drill. When I drill cast, WD40 does a much better job than any of the oils I have tried. Something specifically for aluminum might make sense for your application.
6. Make sure feeds and speeds are on. If it is squeeling and the hole is all chattery, the drill bit is going to wear out faster. Ideally there should be no squeeling. If your RPMs are too high and feed to slow, the bit will wear out faster.
It is hard to give really good specific answers without knowing a lot more details, but just using torque to force a drill bit through is really the worst case scenario.