First, is this a criminal charge or a civil charge? You can find out by contacting the arresting agency and asking.
If this is a civil charge (i.e., you are only facing a fine), then whether you need an attorney depends on your goals. Often times, the attorney will cost substantially more than the ticket. Also, if you appear on the first or a subsequent court date, the prosecutor may be willing to amend the charge to something less offensive or at least lower the fine. If you decide to speak to the prosecutor on your own, do not make any incriminating statements. Just listen to the offer. Although, you may want to offer doing an upfront alcohol and other drug abuse assessment/following through with any recommended treatment to see if that does anything for you.
If this is a criminal charge (i.e., you are facing jail time), you could be charged as a 1st offense or a 2nd offense. A 1st offense is a misdemeanor. A 2nd offense is a felony. Hopefully, you are not charged with a 2nd offense, given your last case was expunged. But either way, you need an attorney on your side for a criminal charge. Contact local, experienced criminal defense attorneys. If you cannot afford a private attorney, contact the local public defender's office. If you do not qualify for public defender assistance, ask the court to appoint a low cost attorney to your case.
Note you may receive a public defender or a court-appointed attorney for criminal charges only, not civil charges.