It seems EL AL will only be sending 737-800's to Luton from November 2013.
They will again go up to 11x weekly (2x Sun-Thu, 1x Fri, 0 Sat) next year but from April rather than June, however all services are operated by 737-800's.
Currently this year, 6 of the 11 flights each week are usually operated by 767's.
Overall I still think it's a bit of a reduction in seats despite the much earlier date of increase to 11x weekly. Through April, March and May this year, there have been 767's on the route, but not for 2014
Even Heathrow on the other hand though seems to have no EL AL Boeing 747-400's next year, only 777-200's.