I've seen the cheat engine, and there's no option to give xp or anything.
1. Get your save file (usually save0.sav from folders) 2. Open any editing tool (online tool like www.saveeditonline.com works fine) 3. Edit any value you see fit. (Exp, item count, etc., experiment yourself) 4. Download it and replace your save file. 5. You are done. Remember to copy original save file somewhere safe in case any coruption occurs to start again fresh.