WordNet sense 1 (continuing in time or space without interruption):

continuous, uninterrupted

WordNet sense 2 (never-ceasing):

persistent, relentless

WordNet sense 3 (recurring again and again):

recurrent, repeated

WordNet sense 4 (continually repeated over a period of time):

running

WordNet sense 5 (persistently continual):

repetitive

WordNet sense 6 (occurring so frequently as to seem ceaseless or uninterrupted):

endless, incessant, perpetual

WordNet sense 7 (continually recurring or continuing without interruption):

constant