Can my friend file Chapter 7 bankruptcy after 2 years of filing one?

No. She has to wait for at least 4 years from the date of filing Chapter 7 bankruptcy. Even if she files Chapter 13 within 4 years of filing Chapter 7, then in that case, her unsecured debts won't be discharged.

Yes, she told me that she got discharged from the debts that were included in the bankruptcy. Can she file Chapter 7 before 8 years? How soon can she file Chapter 13 after Chapter 7?

Well, if this is the scenario, she can file another Chapter 7 again. The answer to your question can she file Chapter 7 before 8 years, is no. I’m afraid your friend will have to wait for 8 years from the date of filing the previous case.
The waiting period for filing another Chapter 7 is a relatively longer period. This is because in Chapter 7 your debts are wiped out, whereas in Chapter 13 you repay debts through a repayment plan over a period of 3-5 years. So, in Chapter 13, debtors usually pay a portion of their outstanding balances.
And, when you’ll be able to file another Chapter 7, you need to calculate the time from when the case started instead of the date you got discharge from your unsecured debts.
However, this time, if your friend wants to file a Chapter 13 bankruptcy, then she can file after 4 years after the initial filing of Chapter 7.
Moreover, you’ll also have to qualify for a bankruptcy chapter before you file one.
And another thing, a court can prohibit a person from filing bankruptcy if he/she has had committed some crime while filing the previous case. It can be failing to commit the court orders, hiding some assets, lying about bankruptcy papers, or if some kind of bad faith was associated. In such a situation, a bankruptcy court can prohibit a person from filing bankruptcy.

Your friend should have assessed her financial situation first before filing for bankruptcy. Because bankruptcy is considered as the last resort to get rid of the debt trap. What if she could paid off her debts by debt settlement?
So as of now, I would advice her to approach a genuine debt settlement company to pay off her debts. The financial advisors of the settlement company can guide her in a better way by keeping her present financial condition in view.
It might happen that your friend's personal loans get settled and she gets rid of her debts.

Yes, in my opinion, settlement should be the best option for your friend's personal loans. Ask her to enrol in a DMP to get assistant regarding it.

Debt settlement would be a great plan to settle your unsecured debt. But it will harm your credit score a lot.

Before answering this question, first, tell me, did your friend get discharge when she filed bankruptcy? Because more than the time frame, that is how soon you can file a Chapter 13 after Chapter 13 or 7, what matters is whether or not your friend got discharge from her debts when she filed for the first time. And, this happens mostly in the Chapter 7 bankruptcy case.