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How fussy are you? If you just want to smarten varnished wood that's had a tough life, clean it with sugar soap and put another coat of varnish on. Would probably help if you keyed it with 320 grit (use the flexible sheets that car sprayers use), run over it with a tack cloth first. If it's not already matt finish, changing to matt would help cover some of the knocks and scratches.
That's what I've been doing for the past 10 years but the effects of accumulated mess from the ceiling being knocked through, plastering and repeated sanding of the walls whilst painting means that the time has come to bite the bullet.