Use a squirt of butane or gas duster gas on the concerntrates before tightly replacing the caps, that will sort them out or rebottle them to the brim. The tetenal E6 ones seal well, which is what i use so butane or gas duster works well. Tetenal working solutions i have kept at just below room temperature in a cupboard under the kitchen sink, in airtight collapsable bottles tightly capped. Longest i have kept a good working solution is 3 months, i usually use them to capacity well before then.
I'm going to try what someone else suggested some kind of gas from freestyle, but where do you just buy butane? like, from a bernzomatic torch gun from home depot?