Are these IAP-105 or are they AP105? If they are AP105 managed by a controller you will need to download the correct versoin of ArubaOS for your controller. In a Controller - AP Deployment, the AP image is distributed from the controller, so there is no way to upgrade APs directly.
ArubaOS / General Availability / Current Releases
From there pick the latest code version which is compatible with your controller.
if you are on IAP-105:
Aruba Instant / General Availablity (Current)
For the IAP-105 you would want the code version: ArubaInstant_Orion