Some transaction/asset types have a Retry feature in the shield history when a transaction times out. Failing that, you can reach to support here on the forums to assist in pushing the transaction through. Support now goes directly to through the devs, so it may take more time than in the past if you need their assistance.
If you know withdrawals from your sending exchange will take more than 2 hours to complete, you should withdraw to an intermediate account/address you control, then send to Incognito with a network appropriate to ensure confirmation in the allotted time.
You can use a hardware wallet like a Ledger or Trezor, if your crypto asset is supported. Or you can use a mobile wallet or desktop software wallet. Most projects will offer at least one official wallet and many maintain a list of safe/recommended wallets.