Don't worry, due to the presence of the conjunction "and", you haven't used the word incorrectly. Apart from the fact you have spelled it wrong, but that of course is another matter. From a stylistic standpoint though, it is considered bad form to use the same word twice in the same sentence unless you do so intentionally for emphasis :) Consequently, if I was editing your sentence I would simply remove the second therefor[e] as it is already implied by the first and as such is an unnescessary drain on the reader's attention.