No, you can do it more than one time. However, you must wait until the following year to make a Roth IRA conversion of the funds that had been recharacterized.
Items directly reducing income. Personal deductions such as for mortgage interest, state and local taxes, and charitable contributions are allowed only if deductions are itemized on Schedule A, but deductions such as for alimony, capital losses, moving expenses to a new job location, business losses, student loan interest, and IRA and Keogh deductions are deducted from gross income even if itemized deductions are not claimed.