There is no restriction on Lucky from rerolling again.
Attack, roll and fail.
Use a point of Lucky, reroll, take second roll.
If that second roll is also a failed attack roll, you've met the requirement for Lucky (a failed attack roll) and can spend another point of Lucky. You then have to keep the latest reroll.
You do have to fail the attack roll, you can't use Lucky to reroll a successful attack roll (searching for a natural 12 crit for example). But if you keep failing the attack, you can continue to spend Lucky points.