can a lawyer charge me a second trial fee?

What does your contract or agreement w/the lawyer state? It's not unreasonable to be charged more when the lawyer has to do additional work, such as getting ready for a new trail. Since it is not predictable how long a trial will take, how much effort or cost will be involved, etc., the norm would be that once you agree to pay for the new services, you pay the whole amount, regardless of whether it took a day or a month. However, your contract or agreement with the lawyer would control, so if it gave you a discount or reduction if the case settled earlier, she'd have to give you that discount.

If you don't pay, a lawyer can sue you or take any other legal or appropriate steps, like any vendor, store, service provider, or creditor could if you don't pay. However,

1) she can't turn it over to the state attorney's office for litigation--they do not do that; the state does not help privage creditors collect

2) You have a right to an itemized bill or statement of charges, and if she is unwilling to provide one, or if she makes improper threats, you can file a complaint with her state bar association.

Look up the Fair Debt Collections Practices Act (the federal law) to see what your rights are and the lawyer must legally do or provide if she's trying to collect from you.