Do you need to file income tax by April deadline if you are getting a refund?

no you do NOT only if you owe .

If you want to receive your refund fast, then yes you'd have to file your income tax return by the April deadline. Filing your return later will only delay the time you receive your refund. The IRS gives you 3 years from the original filing deadline to claim your refund. If you don't claim it by then, the money goes to the government permanently.

Source: http://www.efile.com/what-are-the-penalties-for-not-filing-a-tax-return-or-not-to-pay-taxes-IRS-penalty-list/