Persistent

andauernd

(indefinitely continuous)

anhaltend

(indefinitely continuous)

ausdauernd

(refusing to give up)

beharrlich

(refusing to give up)

beharrlich

(insistently repetitive)

beständig

(botany: lasting past maturity without falling off)

dauerhaft

(botany: lasting past maturity without falling off)

dauerhaft

(computing: existing after the execution of the program)

hartnäckig

(refusing to give up)

hartnäckig

(indefinitely continuous)

persistierend

(botany: lasting past maturity without falling off)

ständig

(indefinitely continuous)

unaufhörlich

(insistently repetitive)