The only ways you can upgrade/be upgraded in those fare buckets:
1) Submit a bid in their online upgrade auction system (YMMV, this is not always offered. Pull up the details of your booking on El Al's site and it should pop up with the option if you are eligible).
2) Free operational upgrade (i.e. both economy and economy plus overbooked)
3) Through the call center, you can "buy up" to a more expensive fare bucket which lets you use points to upgrade. 99% of the time is prohibitively expensive.
4) Upgrade while you're physically on board the plane, which I think costs $700+ (per leg, of course). A little disappointing to spend so much and not even get to use the King David Lounge if your flight is ex-TLV.
That's about all there is...