You need to try to figure out what finish is on there now as some are incompatible and you'll really end up with a mess if you mix things. refinishing kitchen cabinets requires a really good cleaning first, as there's likely a coating of grease and crud over things now, and you won't get a good flow of any new finish unless that is cleaned off first. Also, with cherry, the wood will likley have darkened considerably, and any touchup may have lighter spots if any sanding was required. Cherry is a hard wood to refinish and have look good. I doubt it is varnish...it's probably some form of polyurethane. If you know the brand and style, you may be able to research on-line or call the manufacturer for their recommendations.