keep up

verb

Etymology: From Middle English kepen up (“to perpetuate, maintain, preserve”), equivalent to keep + up.

To maintain; to preserve; to prevent from deteriorating or falling.
“This was the West Lancashire Railway, an ambitious but feckless little concern which, in a life lasting a quarter of a century, never earned a dividend, failed to keep up its debenture payments (despite a dangerous attempt to do so by issuing more debentures) and ended up in the hands of a receiver.”
“The NRA is pumping groundwater into the River Itchen in Hampshire to keep up its flow and is trying to save three streams, the Tong, the Little Stour and the Dour from going dry this summer.”
To continue with (work, etc).
“Non obstante the Change of Religion, the Plough-boies, and also the Schooleboies will keep-up and retain their old Ceremonies and Customes and priviledges.”
“Keep up the good work of entertaining your fans on court Steffi; we know you can do it; your fans are behind you all the way.”
To stay even or ahead.
“They ran so fast I could hardly keep up.”
“Rooney and his team-mates started ponderously, as if sensing the enormity of the occasion, but once Scholes began to link with Ryan Giggs in the middle of the park, the visitors increased the tempo with Sunderland struggling to keep up.”
To ensure that one remains well-informed about something.
“I always try to keep up with (or "keep up on") current affairs.”
To prevent someone from going to bed or to sleep
“The crying baby kept me up all night”
To use capital letters as much as reasonable.