The problem is that said extracts, or rather the active constituents therein, are lipophilic (i.e. fat/alcohol soluble). Fairly often (for economical and toxicological reasons) such extracts are for said reason made with ethanol (or supercritical CO2 but then cost more). Therefore, re-solubilisation is only possible with similar solvents. You may try to evaporate the solvent and reconstitute in glycerol or a glycol. Since an extract (apart from pure resveratrol) obtained by ethanol extraction contains a mixture of medium polarity compounds, the obvious and only “good” solvent is ethanol. Water will only dissolve some constituents, oils only others. Although, you may want to add your solvent of choice before evaporation (just make sure it doesn’t evaporate too!) and not to the dry, sticky mess after evaporation because for a bunch of reasons (some of which are unknown) such a dry or semi-dry (in pharmacy it’s called a spissum extract) will often no longer fully re-dissolve even in the original solvent. That’s one reason why several extracts are only sold as diluted solution. On the other hand, the ethanol % in the final product might be very small and will not really impact your product neither will a possible evaporation of that ethanol.