What can I do with soft biscuits due to air exposure
You can normally refresh them in the oven.  anywhere between about 150°C (for 6-8 minutes) and 190°C (3-4 minutes) should work, ideally taking them out just before they start to brown any more though of course that's a matter of guesswork
Leave to cool on a wire rack, and put in an airtight container as soon as they're cool.
In future, either put the twisted packet in a closed container, or clip it closed, though it may just be that you tried to store them for too long in high humidity.