Often, but check them first. The extension (FLR(M)) is a leave to remain application, so under paragraph 39B of the Immigration Rules each translation must be certified by a qualified translator and state the translator's or company's credentials. Translations made for an entry clearance visa from abroad don't always include those.
A certified translation doesn't expire. It's tied to the document, not to the application, so if your marriage certificate is the same piece of paper you submitted from abroad, its translation is still an accurate rendering of it.
What changes is the standard the translation is measured against. Paragraph 39B of Part 1 of the Immigration Rules sets out what every translation must include: confirmation that it's accurate, the date, the translator's full name and signature, and their contact details. For applications made inside the UK, which covers the extension and later ILR, it adds two more: certification by a qualified translator, and details of the translator's or company's credentials. Your first visa was an entry clearance application, so it didn't need those two. The marriage hasn't changed; the dress code for its paperwork has.
So pull out the old translation and check it against the list below. If everything is there and the original document hasn't changed, reuse it. If the credentials or the qualified-translator certification are missing, get it redone before you apply. That's far cheaper than a request for further information arriving halfway through your leave.