keep up (v.)

• back
• bear
• bolster
• brace
• buttress
• carry
• conserve
• continue
• copyright
• cradle
• cushion
• endure
• extend
• guard
• hold
• keep
• labor
• last
• lengthen
• maintain
• moonlight
• patent
• perpetuate
• persevere
• persist
• pillow
• preserve
• prolong
• prop
• protect
• protract
• register
• reinforce
• retain
• save
• shore
• shoulder
• spare
• stay
• subsidize
• subvention
• support
• sustain
• toil
• undergird
• underlie
• underpin
• uphold
• work