Stay in touch with them out of the session, and bring the storyline in the chat once or twice per week. Give them a little reminder when that happens, maybe pointing out a possible outcome or two (that might be or not be true), like "I wonder how the king will react when he hears that you delayed the rescue of his pet dragon to help a nymph." Sometimes ask them in private what they expect of the game, if they have some character advancement plans, if they wish for any specific piece of gear or history to happens, etc. Basically, be sure that the game is alive in their minds in the time between sessions.
Ending the session as soon as a combat starts might also works, because they will start right at a combat scene in the next session, but unless it is the first combat of the day, you have the responsibility to keep track of anything that might be used (consumables, spells, willpower, etc). On the same vein, stopping right before a crucial scene with a relevant NPC might do the same, but my experience says that people tend to forget what is relevant to ask to the NPC in the next session, but everyone start strong if they start in a fight.
Last, but not least, keeping a journal in a website or forum (even public ones), and instead of updating it as soon as possible, put the session report exactly at the central point between sessions. If you play weekly, post it 4 days after the previous session. If you play bi-weekly, post it on game day in a week you guys are not playing. Not only they have a place to check out any info they might forget, this helps with the "keep them remembering about the game" bit.