freshen up vs refreshen

freshen up and refreshen both are verbs.

Word	Noun	Adjective	Verb	Adverb
freshen up	No	No	Yes	No
refreshen	No	No	Yes	No

As verbs, freshen up and refreshen are synonyms defined as:

Other synonyms of freshen up include freshen, refresh.

freshen up (verb)	refreshen (verb)
become or make oneself fresh again	become or make oneself fresh again
make brighter and prettier	make fresh again