Hi. I made choc ganache using a 2:1 ratio. I left it out at room temp for a day and a half. Its a soft peanut butter consistency- i would have thought it would be totally solid by now, and am afraid to use it to cover my cakes for fondant prep. In the past it was solid and i had to soften it before using- the white chocolate ganache i made at same time is solid....

what should i do? add more choc and wait for it to set again?

You could try putting it in the fridge for about 45 minutes to see if that begins to firm it up....  If so, then you know it is ok to cover your cake....  Or you could melt some more chocolate and stir that through...  Did you use the same chocolate that you used other times? 

There's lots of reason this could be - different chocolate (lower cocoa solid percentage) different cream (different fat percentage) or even different weather. 

If it's not stable at room temp, I'd err on the side of adding more chocolate about 1/4 or a 1/3 of what you used before.