You asked "must I refresh" which would be up to the operator. Whether you should or not is something you have to decide for yourself and depends on how solid your diving was before the interval.
If in doubt, go for the refresher course as a tune up. In the scheme of things the additional cost isn't that great, and you'll have better diving for the rest of the trip.
If you skip the tune up, be aware that many operators do formal checkout dives with new clients. To avoid disputes, others disguise these by taking folks on easier dives over shallow reefs on the first day and observing how they do, before taking them to deeper sites. Either way, diligent operators assess the skills of their clients and try to match the dives with their skill set, so looking good early on will get you more varied diving for rest of the week.
In any case, it's important that you're honest with yourself about your dive abilities, and confident without being overconfident.