Your risk assessment may only need updating rather than re-writing or starting again.
EG: new activities planned and the risks attached to those. Additional needs of members. Change in usage of the accommodation (not sole user/building change)
Risk assessment is one of the documents that must be attached to the REN with Part 1 and Part 2 (Part 2 allows for updating of risk assessment as becomes apparent in the planning process)
Always worth looking at them to refresh yourself as to the risks and to share the findings with your team. No good saying that the girls will be supervised in the playground if no one tells the leaders to do it ( I know it's common sense but you get the idea, you all need to know what the principal safety measures are).
As growly says, if you don't send one with the REN your Commissioner could justifiably refuse permission and without permission the event is not covered by our insurers..
Also a RA doesn't just cover accidents, it is the risk to you and the unit as a whole, so the financial risk, what happens if you have to cancel at last minute, what if the bus doesn't turn up, what if a leader can't go...all should be considered