Welcome on board. No such thing as a dumb question.
No the free offer is a one time only free bet - as a thank you for registering as a new customer. Once you have bet it, it's gone. If you win with betfred you get to keep the winnings only, they will not give you the free £50 stake also. This is the reason why you have to go for higher odds on the free bets. It will then be time to move on to the next bookie.
Reloads are repeat offers of free bets to existing custmers. Bwin and sporting odds are currently the best bookies for offering regular reloads.
Make sure you do them soon