keep up

verb

1. maintain a required pace or level"He could not keep up and dropped out of the race"
2. lengthen or extend in duration or space"We sustained the diplomatic negotiations as long as possible"
3. keep in safety and protect from harm, decay, loss, or destruction"We preserve these archeological findings"
4. keep informed"He kept up on his country's foreign policies"
5. prevent from going to bed at night"The anticipation of the trip kept the children up all night"