Not definitely required, but that would certainly be the quickest option.I've just tested my battery at rest and it is reading 12.1v so does look like a replacement is definitely required.
A couple of long journeys won't touch a neglected battery, but I have rescued them by a long slow charge from a dumb battery charger.
"Long" means long ... I have seen batteries that take a week of slow charging to recover.
"Dumb" means not one of the smart chargers you get these days ... they switch off when they think they're done, unless they have been specifically designed to revive patients that are on their death bed.
It's worth a try if you have an old charger, and if you have the patience!!