Well I think its an excellent idea to rebuild!
Most of the players on your roster have given you pretty much everything they could, and they arnt getting any better because they are so old.
If you are going to rebuild, then its probs best that you go all the way, which is a longer process, but with rewarding results.
Start saving all your cash, and put it towards scouting and building your arena.
Tank next season so you can get some quality draft picks and start training them whilst picking up some impact players around their mid/late 20s to help along the way. Be prepared to demote, and remember, this is a good thing as it allows for some easier competition which allows you to play your trainees and give them as many mins as possible.
Remember to build your arena when ever you can, because the more cash you have, the quicker this process is, because it allows you to purchase some help just in case things start to turn ugly.
Good Luck!