If your system is properly maintained, no. Rare cases of recurrence usually trace to fan failure (replace it), sealing degradation, or significant changes to the home’s air-pressure dynamics.
More detail
A properly designed and maintained mitigation system typically holds post-install levels below 2.0 pCi/L for the lifetime of the system. The fan is the only major mechanical component; modern Radonaway and Festa fans run 7-10 years on average, with some lasting 15+. Failure mode: motor seizes, manometer u-tube fluid equalizes (an indicator that the fan stopped pulling negative pressure), and radon levels drift back up over weeks. The labeled fan-failure indicator at the basement ceiling is the visual signal for homeowners to call for service. Sealing degradation is rare; polyurethane caulk lasts 15-20 years before showing surface cracking. Significant home changes (basement remodel, sump-pit modification, HVAC swap) can shift the air-pressure dynamics enough to require system retuning; the 12-month follow-up retest catches most of these. Annual visual inspection of the manometer plus a fresh test every 2-3 years is sufficient long-term maintenance. Cincinnati post-mitigation drift watch: the most common cause of post-mitigation level drift is fan failure (motor seizes, manometer u-tube fluid equalizes). The labeled fan-failure indicator at the basement ceiling is the visual signal; check it monthly during the first year, then a few times annually thereafter. Fan replacement is a 1-2 hour service call at $300-$600 labor plus the fan ($200-$400). Most homeowners go 7-10 years between fan replacements.