If your desire is to pay it off in 2 months it would be a waste of money to recast.
Recasting takes your remaining mortgage balance and reammortizes it over the length of the loan. So for example, if you had a $250k/30 year mortgage and dropped $100k onto it after 2 years, you could reduce your remaining payments by recasting - your new mortgage payment would be 28 years/$150k (minus whatever other principal you paid during those 2 years) at the same interest rate.
Paying additional principal doesn't result in reduction in future loan payments. It just accelerates the payoff. Using the above example, your mortgage payment wouldn't change after the $100k without recasting but you'd obviously pay the loan off considerably faster.