1) Set a deadline for eliminating Iran's nuclear facilities. If the U.S. takes out Iran's capability, then Israel has no more existential threat to worry about and does not have to take risks to do the job itself.Read the details.
2) Sign a formal defense treaty with Israel.
3) Admit Israel to NATO.
4) Offer a generous compensation package to relocate settlers inside Israel.
5) Pressure the Arabs to purchase the land from the settlers.
6) Provide Israel with a large number of Joint Strike Fighter aircraft.
7) Finance the Red-Dead water project, which involves building a canal from the Red Sea to the Dead Sea.
Of course, no one can seriously expect this to happen.
For Obama to offer a real incentive to Israel might ease Israel-US tensions, but would upset the Arabs--and upsetting Obama's plan to strengthen US-Arab relations.