accelerate
aggravate
beef up
blow up
come again
complicate
concentrate
condense
consolidate
copy
deepen
ditto
do a repeat
do again
do over
double
dupe
duplicate
echo
enhance
exacerbate
exaggerate
geminate
heat up
heighten
hop up
hot up
imitate
ingeminate
intensify
jazz up
key up
magnify
make complex
mount
multiply
multiply by two
parrot
plagiarize
quote
ramify
redo
reduplicate
reecho
regurgitate
reincarnate
reinforce
renew
repeat
escalate
step-up
redoubled
redoubles
redoubling
Hubble
bubble
rubble
stubble
trouble