If you are reasonably fit already, if the ride is on similar terrain to what you are used to, if you don't have to push the pace along, and if you don't mind some pain/discomfort, you could probably do it as is., however if you want to enjoy it it will be better to train a bit.
Sounds like a good challenge to take on (theoretically
), but for us to give any meaningful advice you will need to tell us a bit more.
There are experts on this forum who will have a lot more questions than I have.
Re the planned ride:
Road or MTB?
How many ks AND how many meters of climbing on each day?
How do the "Ks and climbing" compare with your daily rides and your longest ride to date?
How fast will the rest of the group be riding and are you expected to stay together as a group?
How fit are you?
How did you go on the 140 k ride?
How quickly did you recover?
How long ago was it and are you in similar, better or worse fitness now than then?
Do you like unnecessary pain? Or would you rather be well trained and well prepared? ( serious question! )
Are you used to managing nutrition on the bike
Looking forward to hearing more.