Corsair1963 wrote: Sorry, what payload and fuel advantage does the F-15 Strike Eagle have over the F-35A? As I've seen no numbers to support such a claim! Also, I doubt the F-15 is cheaper to own and operate either???
So, again what's the advantage of acquiring more F-15's???

Because if the do not buy them now they will not be able to get more later? The F-15 is EOL. When the line closes they will not be able to get more.
The Israeli uses the F-15 as more than a bomb truck. I think they realized they wanted a second squadron before the F-15 line closed. The A/B models they are currently using are getting long in the tooth. Oddly they had 26 A/B models (22 survivors?). That will leave C/D models left, with the 15Is.
"what's the advantage of acquiring more F-15's?" Two man crew, absolute performance.
For all the things the F-35 can do, it cannot be scrambled to mach 2 and 50k feet as fast as an F-15 with 229's. QRA. Mini AWAC/CIC, the back seater can and have been used to provide local command and control. The US has ~30 AWACS, 15 or so JStars, 40+ Hawkeyes. The Israelis have 3, 1 707 AWACS and 2 G550 CAEW. They use the mudhen as more than just a bomb truck.
Given your username, I would like to rephrase your question:
"Sorry, what payload and fuel advantage does the F/A-18 Hornet have over the A-7E?" As we all know, none.