If she were to be late again, _________

The verb phrase 'were to' is sometimes used in conditional sentences when the likely or unlikely result is particularly awful or unthinkable.
In this case, 'were to' is used to place emphasis on this potential outcome. Consider these sentences:

Example:
- If I were to be sick, I would miss another day of work.
- If she were to be late again, she would have to have a conference with the manager.
- If the rent were to have been a penny more, they would not have been able to pay it.

Note that the emphatic “were to” can be used to describe hypothetical scenarios in the present, future, and past.

Source: grammarly.com