The cap gains exclusion is for primary residence and applies to the sale for that tax year. Single homeowners have the 250k exclusion, married have 500k. The exclusion is for that year so when you filed in April of 2006, you applied the exclusion for the 2005 sale.
You do not need to repurchase another home. You are free and clear as long as you filed correctly in April of 06 for the 2005 sale.
I assume you are talking about a primary residence not an investment property..
