I left my lights on for a few hours and the battery is now dead so i cannot start the bike.

I know if i go to the Honda shop they'll try and get me to buy a new battery.

Can i charge the existing battery instead as its only 1 year old?

Also, does the battery recharge if i can get the bike started and keep it going?

 

Lead acid batteries do not like to be discharged
Sometimes they can be recharged and work fine
But, most of the time, they will charge up but not hold enough power for any length of time
They lose their capacity to hold a charge.
Yes, if the engine runs and the alternator works then running engine should charge up battery to its present (good or bad) capacity
Just remember that weak batteries can leave you stranded.
Yeah, charge it up and hope for the best???