Can I loan someone money with the initial intent that I will deduct it from my maaser if he does not return it? If he returns it I will reallocate that money to maaser and if he doesn’t I will count it as having given him tzedakah?
This is fine, provided of course that the person to whom you lend the money is poor, and worthy of being given maaser money. You should write down the ‘debt’ to maaser, to ensure that you ‘maaser accounts’ are clear.
In general, one must assume that lent money will be repaid, for a fellow Jew is not suspected of being a “loveh rasha velo yeshalem.”