1) At times 2) Sporadically 1) In a sporadic manner 2) Sporadically 
• (adv.) In a periodical manner.
Pe`ri·od'ic·al·ly adverb In a periodical manner. 
periodically 1. Repeatedly at regular times: 'The equipment should be tested periodically. 2. At stated periods; such as, a festival celebrated periodically.
Sometimes or once in a while - perhaps on a schedule
Sometimes or once in a while - perhaps on a schedule