Yes.  Subpart J section 40.213 (e) of  49 CFR Part 40 requires refresher training for BATs no less frequently than every 5 years from the date on which you completed your initial BAT training.

You must complete refresher training that meets all requirements of section 40.213 (b) and (c), i.e. a complete course every five years.

Five years is a long time. Common sense would say that the BAT who reviews the material and practices on a routine basis has a better chance of remaining proficient. In many cases, such as where BAT functions are collateral duties, alcohol testing may be only part-time work, at best. In these cases, especially, practice (e.g., reviewing course material) may be the only means to stay proficient.

Any employer who takes an adverse personnel action against an employee who fails a DOT alcohol test should be prepared to defend the training of the BAT during possible litigation proceedings that may develop as a result of that action. Intoximeters strongly advises Instuctors and BATs to practice positive scenarios and other obstacles on a regular basis to maintain an appropriate level of competence.  If this type of continuing education is documented by BATs and those who train BATs, it will go a long way toward proving that any particular BAT was competent at the time of a disputed test.