up
1.
to make sth stay at a high level :
The high cost of raw materials is keeping prices up.
2.
to continue sth at the same, usually high, level :
The enemy kept up the bombardment day and night.
We're having difficulty keeping up our mortgage payments.
Well done! Keep up the good work / Keep it up !
3.
to make sth remain at a high level :
They sang songs to keep their spirits up.
4.
to continue to use or practise sth :
to keep up old traditions
Do you still keep up your Spanish?
5.
to take care of a house, garden / yard, etc. so that it stays in good condition
SYN maintain
—related noun upkeep