Your friend has 'obtained a pecuniary advantage by deception', which is a criminal offence and also gives rise to a civil debt in respect of the excess premium which was avoided due to not declaring the points.
If she does not pay the 'back premiums', the insurers could seek to recover the money through the civil courts. (Irrespective of whether she repays the money they could refer the matter for criminal prosecution, although this is very unlikely).
However, your friend's biggest problem, if she fails to repay the money, could simply be that the insurance company might refuse to insure her. If so, she'd have to answer 'Yes' to the question, from other potential insurers, which asks 'Have you ever been refused insurance'. That could make it very difficult for her to get insurance; she might find that her new premium is 2 to 3 times the current level. It would cost her far less simply to 'pay up' what she owes to her current insurers.
Chris