I need to file a new t1032 form for 2018 as my return was assesed and needs to be reassed because i recived a new t4a reducing pension amount for 2018

You can either make an "adjustment" to your tax return or "ReFile" it. As you are making a change regarding Pension Splitting, you will need to adjust both you and your spouse's tax returns.

https://turbotax.community.intuit.ca/replies/3639538