It will probably not restart on RTE2 until Desperate Housewives 3 finished its run. RTE2 seem to have designated the Tue 9.30 slot to the high profile US imports.
I believe that they are signed up for 2 more series of Lost, with rumors of it all culminating in a movie.
Personally I lost all interest early in Lost series 1. It quickly became clear that there is no possible way they could deliver a satisfying conclusion. Any explanation they come up with for the goings-on on the island is definetely going to be stupid.
It kinda reminds me of Twin Peaks, which IMHO followed a similiar path in obscurity and daftness.