Before you replace the keyboard, do some work to narrow down whether it is a hardware problem or a driver or Windows problem. 

Here are some things to try:

• Try a power reset (unplug AC adapter, disconnect battery, hold down power button for 30 seconds to discharge flea power).
• Use the keyboard troubleshooter. Troubleshoot settings | Additional troubleshooters | Keyboard
• Connect an external USB keyboard and try that for a while. If the issue also occurs with the external keyboard, then the issue is something in Windows or driver. If the issue does not occur with the external keyboard, then it's likely a hardware issue with the onboard keyboard and it may need to be replaced.
• Try in Safe Mode to see if the issue occurs there.
• Try the Windows on-screen keyboard. If on-screen keyboard also exhibits the issue, it could be due to corrupted system files. Run SFC (System File Checker) scan on your PC to repair those files.
• Try in Linux (by booting from a flash drive with Live USB install of Ubuntu, Xubuntu or other)

Dell keyboard troubleshooting guide
https://www.dell.com/support/kbdoc/en-ca/000131432/keyboard-usage-and-troubleshooting-guide

If, after all that, the issue is isolated to the onboard keyboard, then yes, you would need to replace it or use an external USB keyboard.

Parts-People has genuine Dell keyboards for your laptop model. Given the age of the system, consider whether you want to spend money on a replacement keyboard, or save up for a newer laptop.

Parts-People has several keyboards in stock for your model. They have standard US keyboard, French Canadian, Spanish, US International. They ship to Canada. If you want a local seller, you could take the part number(s) from Parts-People and search online for local seller of that part number.