Whether you can be sued again depends on (a) whether the first case was dismissed with prejudice; and (b) whether, after the case was dismissed previously, the finance company got relief from the dismissal. (That can happen if they show that it was the previous' attorney's fault.) You may wish to check with the attorney who represented you in the first lawsuit or check with a lawyer.
Disclaimer: The above does not constitute legal advice. This is particularly so because I don't have all of the facts. Simply put, I am not your lawyer and you are not my client and my answering a question according to Avvo's rules doesn't change that.
Yes, you can get sued a second time for the same debt if the first case was dismissed by the court without prejudice (which is typically what happens then the plaintiff fails to appear in court).
The only difference in the defense would be whether the second case is barred by the 2 or 4 year statute of limitations.
The dismissal you describe is probably not considered "with prejudice," because the court did not rule on the merits of the case, it was for failing to appear at a hearing. The second lawsuit must still be filed within the applicable statute of limitations period. There are many different limitations periods, so it is not safe to assume that it is four years from the date of last payment.