If fleas are prevalent where you are and your rabbit(s) are ever outdoors where they would be exposed to getting the fleas, it's up to you if you think it's needed. Though usually with rabbits you only treat for fleas if they end up getting them, as rabbits aren't usually outdoors on the ground very often, where they most commonly would pick the fleas up from.
Regular Advantage(imidacloprid) and Revolution/Stronghold(selamectin) are both considered safe for rabbits, with Revolution being the better of the two as it's generally considered safer and also treats mites. NEVER use frontline(fipronil). It is toxic to rabbits.
MediRabbit (fleas and treatment in rabbits)