You do still have a source of propellant on your stranded spacecraft, because your crew all have EVA suits. In other words, they can get out and push. As far as I know, as long as you remember to get back into the capsule before the propellant runs out, it can be refilled as many times as you want. It might take a while to get your orbit adjusted the way you want it but in an orbit like the one you describe, it doesn't take a lot of dV to drop your periapisis into Kerbin's atmosphere, and from that point on you should be golden. Better than smashing into the Mun, at any rate, which is why I did it.