To raise the stakes of a hand of poker
With three aces and two jacks, he thought it was safe to up the ante
(dispute) To take an action that raises the stakes, i.e. that increases the chances of conflict.
To make something more difficult.
When runners cross-train for events, they often up the ante by running on sand.
To make something more desirable.
The school system cannot raise teachers' salaries, so they are providing better benefits as an effort to up the ante.