for a few weeks i wouldn't decant the beer, but i would get it into a sanitized smaller vessel with little air space and a sealable cap (don't tighten it all the way though, you will probably have a bit of residual activity or at the least CO2 still coming out). i like to save yeast for re-pitch, or starters that are waiting for their wort, in 1 liter screw cap jars that can be easily sanitized, filled to the top with the beer they were living in, or else topped up with boiled and cooled water as necessary. after a couple weeks storage, i would not make a new starter, i would be happy to pitch that yeast, but you can always feed it a bit of wort a few hours before pitching to get it active. to do that, i decant it while it's cold (since some yeasts will go straight for the surface as they warm up), let the yeast cake warm to room temp, then add similar temperature wort; while i am cooling my wort i run some off and cool it quickly in a water bath.